Mass Effect series - in a time when Sci-Fi goet really corny and wack, Mass Effect was able to bring it with a mature, realistic slant. The Races and politics and backstories were extra detailed. I never played a game that needed its own little wikipedia for all the information....and i read it all.
Assassins Creed 2 - the series woulda got some love from me but 1 and revelations were mad disappointing. AC2, however was perfect. Great blend of dungeon and open world, great and varied missions. BY FAR the best story pacing, and supporting cast. Its just hard to find a flaw with this game.
Uncharted 2 - train level.....end of story...
Red Dead Redemption - my hands down favorite, the atmosphere, the game play mechanics, the open world everything. The fact that the mexican desert looked different than the American on...obvious CULTURAL differences based on what area of the map u were in. and not to mention what i feel is one of the best protagonists in gaming ever with Marston. By the end of the game you really are hurting by what happens. its just so flawless to me.