here comes the n00b question.
Does threat gain = damage done, by that i mean, if you start doing more damage than the tank will you eventually gain aggro, or does the skills he uses to control aggro have nothing to do with damage done?
No it doesn't work like that. Typically tanks won't do huge DPS (except Pallytanks in SH
They keep aggro because of abilities that generate additional threat over and above what they generate from damage.
From playing a few aggro sensitive classes (Enchance Shammy pre-2.3, Shadow Priest) I'll have to say Pallytanks have the best Aggro gen out of the 3 tanks.
If the guys knows how to gear he just never loses aggro. It's awesome.
Druid tanks are second with some really good Aggro gen but sadly I tend to find a lot more bad Feral Tanks then Bad Prot Pallies.
Warriors are a resounding last. If I can get a group without a warrior tank I feel a bit better because sadly while they are the best tanking class they have an overabundance of fools who have no idea about threat gen post-BC who think Sunder-Spam is still how it's done.