It ALL depends on the type of player you are and what your personal preferences are. If you favor agility and stealth like I do, the hunter would be your favorite probably. And the cool cloak as a perk doesn't hurt. If you like dealing massive damage with grenades, melees, and supers, at the cost of a little agility and armor rating, warlock would probably be your favorite. Self revive for sunsinger is also a nice thing to have. And if you enjoy standing and fighting in the midst of the battle with lots of armor, but little agility, titans are the way to go. They all have their ups and downs, but it all depends on personal preference.