Just going through the classes at the moment, love the Challenger. Strong class that, huge melee damage and the self rez is invaluable. Medic is a good all rounder and his light machine gun is actually very good for keeping elite mobs staggered. Gunslinger (the class which comes with the Ultimate edition) is a little more tricky, high dps but quite weak, a glass cannon, which you have to make really good use of weapon swapping to get the most out of. Tough solo class but good for co-op. Just trying the Hunter class next and then the Dog Handler class