Been having a long debate about this one,
But in S2, my vote goes to the Devastation Evoker - they can be good, but their chronic witness is survival - literally every other dps spec, has something. I think after that might be warriors.
Warrior can be great for defending others, but in my experience they die a lot in m+
I mean a good barometer is to see how often they die in a group, although player skill goes a long way.