Up until now the roles in raids were pretty obvious, pure DPS classes did damage, classes with the ability to heal healed and the warriors tanked. Come expansion time it seems the roles changed a bit, while the enchantment shaman or the shadow priest will likely be seen more in raids, the biggest change as I see it is the change in the tanking monopoly.

Up until now raids were depndent on warriors. Lacking rogues? Thats ok we'll bring more hunters, only 3 priests? Thats ok paladins and druids will fill in. Only 2 warriors showed up? Ok raid cancelled. This was and still is a very likely scenario that we have exprienced in the last 2 years. Now something have changed, Blizzard decided to give us 2 additional viable tanking classes. The real question is are this tanks really viable, and if so, how do they stack against a warrior and against each other?

I've decided to put some tanking categories and to see what each class brings to the table, so lets start.

Aggro generation
Perhaps the most important aspect of tanking, the ability to generate most aggro and keep doing it for the duration of the fight.
The warrior have the most tools to generate aggro. Sunder, heroic, revenge, shield slam and devastate. Lets say that a warrior have no problem holding aggro.
The Druid is a bit diffrent, druids use very few attacks to hold aggro, but their attacks generate the most aggro out of all 3 tanking classes. In an aggro competition between all classes on a single target a druid will most likely come out on top. While druids have several weaknesses that I'll discuss later, aggro generation is not one of them.
Out of all 3 tanking classes the paladin is by far the most unique when it comes to aggro generation, unlike the 2 other tanking classes, a paladin recieve his aggro from holy damage and not physical damage. A paladin uses combination of seals (Venegance alliance, Righteounes horde), judges, Concecration and Holy Shield to get generate his aggro. I'll say that out of the 3 classes a paladin might draw the least initial aggro, but his aggro ceiling is much higher. Items with spell damage on them really pushes a paladin threat up and allow him to match and even surpass his counter parts.

Survival
A very crucial subject that allways comes up when discussing viable tanks, the most common argument against both druids and paladins today is that while you can hold aggro like a warrior, you just can't take the damage. Unfourtently as of now they are right, but come expansion that will change as well. First lets look a the pure numbers:

Physical mitigation: (Considering all tanks are speced for it)
Warrior: 10%
Paladin: 6%
Druid: ? (Not really sure)

Spell mitigation:
Warrior: 16%
Paladin: 11%
Druid: ?

I didn't follow much of any feral tree changed that didn't made it to live (But expected to be in TBC) like I did of the paladin, but it seems that once again druids got the worse end of the stick again considering damage mitigation. The fact both warriors and paladins can parry, block, use consumable and seems to have less "Oh shit!" skills like last stand, shield wall, lay on hands etc. Seems to me really hurt druids chances of tanking end game content. However druids will have most dodge/armor/health out of all tanks, I don't know if it will be enough considering what else they lack. I really like to hear from druids about this subject.

Taunting ability
This is an interesting subject, most end game content bosses are taunt immune. Taunting ability seems more like add/trash tanking or aoe tanking kind of thing. Our of all 3 classes the paladin have the best taunt (40 yrd range + affects 3 targets), but its the hardest to execute and got the longest cooldown. Besides that both warriors and druids have an AoE taunt (Alltough the paladin is far superior when it comes to aoe tanking thanks to concecration) and also able to charge their targets thus elimanting the issue of no range on their taunt. I'll say this is pretty balanced.

"Oh shit!" moments
This is kind of "thinking outside the box" when it comes to tanking. When you look at certain fights in the game (Firemaw, Huhuran, Twins, Heigan, Sapph) when I wish my tank could have just shield or heal himself. Warriors are really straigh forward tanks, who are not really self sufficient, their "Oh shit!" moments strong point is during a tank and spank kind of encounters (Loatheb, Thaddius, Maexxena etc.) when last stand and shield walls are defently a great thing to have. In stage fights and tank swapping I think having druids and paladins who are less dependant on their healers can really save a wipe sometime (Like shapeshifting out of some movemant imparing effect or shielding an exploding bug / blizzard combo). I feel having multiple tanks who can do diffrent things can be a diffrence between a kill and wipe.

Conclusion
I feel all 3 tanks are viable and can really work well as a team. I think each class cover the other classes weaknesses quite well and can perform at some situations the tanking job better. Druid seems to be a very good tank against a mob who does high amount of physical damage and can't crit (Patchwerk) or against a boss who can cast polymorph or movement imparing effect (Jin'do comes to mind), while a warrior works well against a fear mob or a berserk mob, and palas I feel are best suited for AoE tanking and stages bosses such as Twins or Sapph.

Hopefully come expansion we'll have 3 viable tanking classes, I think it makes end game raiding much more fun and interesting.

Edit: If allready on this subject might as well post my pala tanking build: http://www.wow-europe.com/en/info/ba...00000120000000

On druids, consumables have been promised back for druids and also with the recent bear change have no more HP than a warrior.

Druids ability to tank mainly will come down to will Blizzard itemize druids with tanking gear. So far based on quest rewards it would seem to look hopeful but there has been very few epics for tanking except the ring from Karazhan honor, ring from Badges of Justices, and the Earthwarden. In fact, most the best tanking gear for druids at the moment is actually greens.

I suggest editing your post so it says what you mean ;)
I assume here you really mean avoidance via parry and dodge?
From what I have been reading the agility to dodge ratio for druids has been improved so that a druids dodge is going to be about the same as a warriors dodge and parry combined.
If it works out like that then the main difference is going to be Shield Block and its effect on Crushing Blows.

As Cryect mentioned druids are supposed to be gaining the use of potions again but what they will allow us is unknown at the moment. He is right again on a druids viability coming down to the itemisation, if they put in better versions of a few of the green items it should be fine.

Personally I am expecting all three classes to be viable tanks if geared and played correctly.
Having said that I still expect warriors to do the main boss tanking while druids and paladins tank the encounters which play to their strengths.
However all of this comes down to how the encounters work so until we get to have a go at them its all conjecture.

i see a lot of assumptions and statements without any evidence to backup:

Why would the aggro ceiling be higher? Either the ceiling is at the blizzard boundary, which so far afaik no raid has ever really encountered, or its an ability-imposed limit like broodlord.

Conversely, doesn't this mean the paladin is restricted on aggro by his mana? What happens when the paladin goes oom or if a boss mana drains...

I really don't know if a tank that can heal themselves is important. The entire point is to be generating threat per second so DPS can attack and healers can heal. Are we going to hear constantly on vent "ok everyone stop attacking I'm healing myself"? If blizzard let paladins have a talent that causes self-heals to generate massive threat then yes, I would agree this is a good idea. But since paladin heals cause the least amount of threat...

so far my experience in 5 man heroics on beta is that druids tank better than warriors due to the multi-mob pulls. warriors who are spec'd prot, play smart, and geared (thunderfury helps immensely) can do a great job as well but its very easy to pull aggro off them - my warlock has pulled adds off with just dots ticking. paladin tanking in 5 mans has not been very good so far in my experience, but it could just be I've been grouping with very bad paladins. would like to hear more on how groups with paladins as tanks have fared in shattered halls, karazhan, TK, etc.

I'm guessing he means the aggro potential over time? I'm honestly not sure if their initial aggro is that much lower than a warrior's, either, actually. An Avenger's Shield to start with, then a Consecration pretty much locks down mobs for my paladin in groups right now. From there I can just let Seal of Vengeance do the work for me and judge it where needed.

I see paladins being a very reliable offtank, moreso than druids actually. Could you imagine if paladins had the tanking capabilities that they do now, back in initial release? A paladin offtanking Golemagg's dogs would have been pretty awesome.

Paladins have a talent to turn heals on them via other sources into mana, which will mean they will effectively have infinite mana in high level boss tanking situations. This is a massive advantages for paladins as 1) they can start strong - both warriors and druids start with little or no rage where as paladins will begin with a full mana pool 2) they can keep up the same (or a similar) level of threat when not being attacked - unlike warriors and especially druids 3) they can toss a BoP/heal/insert support ability here if needed, bringing the tank role of protecting raid members more to reality.

I'm looking forward to seeing how paladins perform in serious content

Edit: added quote

Spiritual Attunement is a core ability, by the way, not a talent. It starts off at ~level 18 at 8% of the heal on you turned into mana, and caps out at 10% at level 66 with rank 2. There's also a set bonus from I believe tier 5, that increases the amount of mana returned by another 10%. Interesting set bonus for a tank, where are the ones that increase rage generation? :P

Edit: That's a good point. I don't think you'll ever see paladins tanking a boss like Heigan.

I think what he means by aggro ceiling is that a paladin's threat conceivably scales the most, thus being able to put out the highest threat per second. SoR alones scales at 19% of total spell damage in unmitigated threat per second. It's definitely a blanket statement though, and depends a lot on how they intend to itemize. In a 5 man setting mana usage can be a problem, but I wouldn't imagine in a raiding situation with hard hitting mobs it being a very large issue, as the amount of incoming heals is greatly increased. It would be interesting to see someone more mathematically inclined than I compare spiritual attunement vs. rage in terms of healing->threat conversion. Contrary to the OP, I think initial aggro will be the paladins strong point. Avenger's Shield is a very hefty amount of opening damage.

As for self-healing, it's a boon in 5 mans, as it's possible to spam heals on your self if the healer gets CC'd, but probably mostly worthless in raid settings(as with all things, it depends on the encounter...). Finally, I haven't gotten very far in the beta; but I have tanked some of the intial instances. I've been a tanking paladin(when I'm not raiding) pretty much since day 1; but that's not exactly common. If paladins are having trouble tanking in your 5 mans, it's probably out of a lack of familiarity to the task, not inadaquate tools to do the job.

Tanking golemagg's dogs? I've done that for kicks already. Go search for "kaganos" on google video to see what paladins are capable of pre-2.0. Curiously, we had the ability to tank even easier pre-1.7, when JoF/consecrate produced about 3000 threat. Itemization was non-existant however.

Yeah, I mean when learning the encounter, not when the instance was already tired and farmed to hell and back. :P But you're right, threat-wise paladins were very strong before 1.7 with the old JoF and Consecration.

I think the trick is going to be seeing how many ways the item budget on paladin and druid gear needs to be stretched to make them effective tanks, and whether or not it's possible to do that. You can have all the ability to tank, but you also need gear at least "this high" to tank something meaningful.

Possible ways of spending budget on tanking gear:

Warrior: Dodge, Parry, Block, +defense, +resilience, STA, STR, AGI, +AC
Paladin: Dodge, Parry, Block, +defense, +resilience, STA, STR, AGI, +AC, INT, +Spell Damage(since threat is scaled by spell damage as well as melee)
Druid: Dodge, +defense(note that they get significantly less out of the stat), +resilience, STA, STR, AGI, AC

So it's easiest to create druid tanking gear, and hardest to create paladin tanking gear within the constraints of an item budget. It'll be interesting to see how ilvl-equivalent tanking sets turn out.

I think ultimately that in 5-mans we may well see competent, well-geared druids and paladins used over warriors in AE situations due to the fact that they seem to generate more threat in those situations(just a gut feeling based on a few TBC beta instance runs, nothing more). Beyond that, I'm honestly not sure. I'm sure there will be a lot of experimentation, and once we have raw numbers to work with regarding threat generation and overall mitigation on 70 content we'll see some conventional wisdom developed.

http://forums.elitistjerks.com/viewtopic.php?id=9598
http://forums.elitistjerks.com/viewtopic.php?id=9494

Those threads might be worth looking over if you haven't already, they have some related info. :)

I did want to mention that pallies taunt is not harder to use than warrior taunt.

/cast [help] Rightous Defense; [target=targettarget] Rightous Defense;

If you are targetting a friend, it will taunt 3 things attacking them to you, and if you are targeting a foe it will taunt 3 things attacking their target onto you. Assuming their target has 3 or less things on them this is much more valuable, and you cannot "waste" taunt if they are targeting you the instant you hit it.

Also...

Paladins can raise their threat pretty high with +damage gear, but as the poster above me noted this lowers the item budget they can spend on survivability. This is a tradeoff Druids must make as well, balancing str and attack power with sta and agi.

Warriors Agro does not scale quite as well, but it seems their survivability might scale a bit better, and it certainly starts pretty high. This may be slightly compensated for, if soem of the Beta changes to prot go through that help pally survivability.

This isn't really that hard to figure out. There are too many people playing DPS classes and too few playing healers, therefore the perceived threat comes from a fear of a min-maxing raid group taking the rogues that can shift and heal over the ones that can't.

It really depends on the encounter. Can you imagine a paladin trying to tank in a Razuvious-style encounter where he can't go out of LoS? So... every 30-60 seconds he gets mana burned, loses all threat generating capacity, and we have to heal him way more than a bear or warrior? Similarly, any type of encounter where you have the possibility of getting polymorphed, a bear is usually ideal.

1) You are still more limited by the UCD than rage at the start of an encounter, especially if you are spec'd deep into protection. 1 bloodrage is enough for a 2 rage revenge and 17 rage slam, that should be more than enough threat to get initial aggro and help the rage come in.
2) This is probably where warriors are the weakest, I think they'll be a poor choice for any multi-target or low damage offtanking situation.
3) Warriors have the ability to intercede and take a hit for someone else.

Paladins will probably excel as an offtank in a low rage/low splash damage environment or tanking multiple weaker adds (they would be awesome for a fankriss bug tunnel). Since they won't be limited by incoming damage to generate threat, they'll also probably excel at tanking "farm" content (e.g. Onyxia when you're in t2 or t2.5).

It's not really hard to figure out. Rogues are a very one-sided class, regardless of the spectrum of the game you're at, so it's easily understandable when they get annoyed at druids being capable of sustaining solid melee dps. Tanking is something different though, because even warriors are two-sided. If you bring a druid in to tank, the warrior in your group can switch over to do dps.

That said I don't dislike druids doing dps, infact I really like Mangle as subtlety spec, 350 rupture ticks at 70 is good stuff.

Erm what? What do you mean by can't go out of LoS? A paladin would at most be offtanking one of the adds.

Other than that confusion I mostly agree with your points. I feel paladins will fit in an offtanking role very well.

My pallie is a pretty darn good tank on live in non-raid instances. With a bit more itemization he will be incredible. I specced 40/0/11 and have no problems holding aggro over any DPS class in the smaller non-raid instances (especially when I am being healed).

It's obvious that pallies will be the best multiple target tanks, but the real question is will they be itemized well enough to have high enough HP and aggro generation to effectively tank raid bosses. It kindof stinks that my guild is not raiding at the moment, as I would like to have a shot at doing some legit MTing before BC.

I don't think it'll be very viable pre-TBC, but as you get closer to and reach 70, there looks to be some very solid paladin tanking gear right now. There are some extreme oddities in the set bonuses(Retribution Aura bonus?), but the gear itself looks good.

http://www.thottbot.com/beta?set=623

That entire set looks pretty strong as an entry-level raid tanking set at 70. 106 Defense Rating across 5 pieces isn't bad at all, especially with the other stats(all of which seem needed by paladins, STA, INT, MP5, Defense), and a pretty nice 2 piece bonus.

Could we just make a shirt "Buff Rogue Utility in PvE" hand one out with the collectors edition and be done? I think everyone who's ever watched a rogue on patchwerk or ebonroc agrees. Even blizzard seems to be getting the point: Aran and blindeye are good examples of why I love rogues in TBC. The only sane solution to blizzard's "damage/minute is the currency of wow" base rule is to make damage output about equal between classes. That means everybody needs to bring something unique and special outside of their damage to a raid because raid dps is determined by how many members of the raid are on dps duty. This would be why hunters are in need of a pve buff, and why cat is sketchy in raids (both have marginal to irrelevant utility) If kick/stuns/poisons are relevant to boss fights, there's a reason to bring rogues.

That might be true in practice, but there are plenty of mobs who zip threw targets (pre-Cthun trash or Sartura comes to mind) that by the time you casted your taunt the mob allready changed target.

As for the aggro issue, I believe a paladin have the weakest initial TPS (Threat per second) compared to a warrior or a druid, but that will change drasticlly with gear.

Oh? Perhaps our priests/druids are uncommon, but they have had some interesting verbal battles over just that. Especially before the "priest patch" gave holy more solo grinding viability.

People who play healing classes and enjoy the role might tend towards slightly less competitive personalities in general, but I suspect it also has something to do with having an almost guaranteed raid slot.

Actually, that depends.

Worst case scenario: the CLIENT interprets "targettarget" and the server recieves a message $latency seconds after you hit the button to RF the person MobX was attacking $latencyx2 seconds ago. Thus if the mob changed targets within $latencyx2 seconds your RF is wasted.

Best case scenario: the SERVER interprets "targettarget" and the server recieves a message $latency seconds after you hit the button to transfer MobX's hate from whoever his current target is to you. Your RF can never be wasted, regardless of lag or roaming agro.

Depends on your spec, your teammates, and your target.

If the target is Undead or Demon - Exorcism gives you a ridiculous initial agro dump.
If you are specced 31 Holy (Holy Shock), 41 Prot (Cpt. America), or 41 Ret (Crusade Strike) you can Dump a big hit to start things off.
If you are rolling with another pally to drop Judgement of Crusader for you, or this Mob will die shortly, you can drop Judgement of Rightousness on the mob for a decent chunk of hate.

In all cases above, Rightous Fury and ImpRF make the holy damage significantly more effective than normal damage.