Explanation for my UI-
A- This is the area I'm usually looking at during a fight. My eye focus moves from Omen to my HP/Mana bar, and all of the most important stuff is within there. The area is also small enough that I can see everything with my peripheral vision, especially with looking at my shot timers, (Quartz) which is close to the middle. I'm usually looking at Quartz. Not coincidentally, Quartz is very close to my character's feet, and it's very easy to know when fire happens.
E- Although slightly bigger, I put all important information in this area. If an area is in E but not in A, it means it's not as important and I don't look at it as much. It's mostly my CD timers, MT's, MT's targets, MT's target of target, and making sure my pet is attacking the right mob. Even if I say I don't look at it as much, I still look at all of them within every fifteen seconds, and I pay a lot of attention to the CD bar as important CD's approach popping up.
B- Not shown here, but this is the bar for my pet's target.
C- MT's, MT's target, MT's target of target.
D- There's is where my WIM window goes. Hidden for privacy. NECB is right above it, sometimes I'll want to look at it.
Off the top of my head, the mods I use are-
Pitbull
Grid
Quartz
Hourglass
WIM
Prat
Omen
Recount
Elk's Buff bars
NECB
Mappy
CTraid Assist