Drk = more AOE damage, less defense.
War = less AOE damage, more defense.

If your healer is good, your gear isn't terrible, and you actually use your defensives correctly... then Drk will clear a dungeon faster.
This applys for lvl 30 - 80 dungeons.

If warrior had inner release for every big pull then it would trash drk in Aoe damage, but sadly it does not.