I found this on
SA (not public forum - need account to see thread), which in turn leads to
the official forums (click this link if you don't have an SA account) - insert cliched catchphrase about diamonds here.
Short form: Zyph-Maelstrom (who as far as I know does not post here) rooted through the Armory looking at talents of level 70 characters (albeit with a flawed methodology - he gets his list of names to scan from Allakhazam (obligatory fuck allakhazam)) then isolating to people who have 31 or more points in one tree. Reasonable, since I can't think of any intelligent build offhand that doesn't. After figuring out those numbers, he further culls by determining who didn't take the key 31 or 41 point talents in those trees.
His findings are relatively unsurprising - people hate Slow, Circle of Healing, Endless Rage, etc. - but the standout is that the majority of heavily Holy-specced priests skipped Lightwell. Mind you, he has some really

findings (and if we don't have that emoticon, we really should), such as "Dark Pact is unpopular with Affliction warlocks" - there is an allegation that he meant Contagion, but his original post clearly says "Dark Pact" - but the methodology is fairly sound.
I would like to meet this insane 1.4% of mages though that put 31+ points into Arcane but skipped Arcane Power.
(hooray

is in)