I was quite disappointed with Dark, I made the mistake of expecting the life-stealing solo juggarnaut that Death Knight was in WoW and got this weird clunky mana-tank that is "viable", yes, but excels at nothing except emnity generation, which is hardly necessary, relies on the healer (particularly with no self heal outside grit) and lacks in multiple factors.

Mediocre aoe, moderate dps, poor self-heal, poor mitigation below 70. Dark looks cool, but it ends there, as a class it's not particularly exciting in my opinion.

Since we're on the topic of sustainability, which of the other 2 tanks is the best for self-sufficiency?