I am going to have to go with Fallout 3, even though I yet have to pick it up. 

But my list also entails; Dead Space, Resistance 2, Red Alert III, Fable II, FarCry 2, STALKER: Clear Sky,  Left4Dead(maybe...if its too much multiplayer focused I will probably pass since I have like no time to put into a huge multiplayer game with school), Yakuza II, Mirrors Edge, Valkyria Chronicles, Brothers in Arms, Silent Hill: Homecoming, Saints Row 2, Midnight Club and still have yet to pick off Megaman 9 off PSN...