I don't play a warrior, but I have a pally and DK tank and I MUCH prefer playing the DK. Mitigation on the pally is nice, but when it comes to those big bursts, it's not like I can't pop two cooldowns on my DK (with only 1 or 2 minute cooldowns). But key to me is the flexibility. My DK can interrupt, he can easily grab that annoying caster or ranged guy, I can pop off several huge AoE threat moves before the mobs even get near the party, and my cooldowns are available much more often. That and I can use a giant two-hander... and army...