Personally, all of em'. They're each fun in their own way. I like spy because it's totally unique from all other FPS games and I love being able to hunt down specific enemies. The only class I don't like is the Sniper but I do score the most points on average with him, its too frustrating to be attacked at such a long-range with no way to attack. That's why I hope the Huntsman eliminates a lot of Snipers using the rifle.