Alright here is my OPINION; note this is not fact. Keep in mind I'm going to be talking about the PvE aspect as I do not have experience in PvP to make assumptions. Anyways here's my thoughts (keep in mind I am biased towards hunters as that's what I play). Each class has their own set of skills. Let's first start with survivability. Titans when subclassed for it can be bullet sponges(more so than other classes anyway). So they have built in survivability by just taking more damage. Warlocks have survivability by killing the thing that is killing them faster. (Think glass cannon). Then you have the hunter. While they can't absorb as much as the Titan they can still take a punch (when subclassed for max armor). But they can depending on skill survive a lot more than any other class through use of built in skills think invisibility and the insane mobility a hunter has. I find I am typically the team medic and actually if I go down it results in a wipe more often than not. In terms of supers, warlock's sun singer is generally the most helpful. With Titans defender coming in at a close second. In terms of straight overall damage Titans take this one with hunters Golden Gun coming in as the highest single target damage(if wearing the exotic helm to give 4 shots). Although the hunter is much safer doing so. Too many times have I seen a Titan Leroy Jenkins and rush in a super only to get demolished instantly. While that is fault of the player not the class, it still draws the point of the Titans super is much more risky than the hunters Golden Gun. In terms of grenades all the classes generally have the same grenades just different elemental effects on them. The hunter has the exact same grenade in both classes with one being solar(gunslinger) and one electrical(blade dancer someone tell me the correct term for blue). More so than anything it is the skill of the player vs the class. Someone who knows their class and plays it well will do better than someone who has spent a day or two on their class.