If you want to be the ultimate tank, pick a Guardian. We Guardians get the best aggro, shielding (IE upgrades to Intervene), defensive abilities, and a few buffs (of course, centered around taking less damage/getting more health or parry). When I say upgrades to Intervene, I don't mean every 10 levels only after your current version is outdated. I mean multiple within 5 levels. I have 4 Intervene-like abilities (not counting Intervene), and only one even cons yellow to me, and I'm level 24. And then there's the level 50 Guardian ability (well, one of them), Guardian Sphere. Shields everyone in the group. If SOMEHOW your taunts fail you, you can take the damage for them.