Great question. For me, definitely Red Dead Redemption. Great atmosphere, great gameplay. It was the game that pushed me over the edge in getting a console. It did many brilliant things. Some may complain at it being too big, but it was the wide-open expanse that made it feel authentic, giving you unparalleled freedom. I wouldn't be surprised if Rockstar is planning another RDR for the next generation of consoles after they release GTA 5.