Since you can only have 1 elite in your skill bar are likely going to want 100 blades (more of an offensive tank) or gladiator's defense (more of a true tank). 100 blades goes well with an enchantment spell where you gain health each hit. That makes you a little truer tank. The advantage comes not so much w/ the dmg done but w/ the adrenaline gained by it. Gladiator's defense just owns w/ regard to tanking.
100 blades is found in the breach on a charr named stormbringer. This is extremely easy to get. Bring a hench warrior so he will use the attack on the both of you.
Gladiator's defense is found on the last dragon before Glint. This is tougher to get but just because it takes longer to get to.
I prefer 100 blades but understand how people go w/ gladiator's defense.