If you are a well equiped tank you can generate aggro wtih all 3 tanks just as well and not lose it. The ones who lose it doing something terribly wrong. Howerver If I had to bet on someone It would be DA. Many dps skill and tank stance at the same time along with 2 aoe aggro skills beside the single target ones. But let's not give the wrong impression here. Give love to all 3 tanks they are sexy equally with their own style. After all they are never enough are they?