I see why you would say warlocks are the best. However I disagree survivability on a Titan is much stronger in that I can bubble to stay safe and keep the raid members safe at the same time buffing (preferably with weapons if light) and my mele provides a shield which on the Templar phases and actual fight is extremely useful. I get self revive is cool but I think the Titan offers more to the raid. Hunters need something like that maybe the third subclass will provide it.