I've dabbled in all 3 like you've mentioned and while I love my Hunter (Gunslinger speaks to my style as a sniper), I have to agree that Titan is probably the most fun class to play. Having access to shoulder charge, fist of havoc, fist of havoc superman style or force barrier and a giant bubble of love that also become an enormous flash bang (helm of saint 14, so troll) I have a good time rolling with my Titan. However Warlocks, mainly Sunsinger, jump out to me as the "best" class as they can do everything except stealth. Literally. Locks are definitely the favored class as far as advantages to their kit. Xur realizes this and balances the game with sun breakers for them every weekend. :)