For me, the best games of the generation were:
Mass Effect 2 - Arguably the best game I've played in the last five or so years, this is exactly the kind of game that, as a kid, you wanted them to make one day. A hybrid of different genres with an excellent story, wonderful, deep characters, and actual, satisfying gameplay. I think I've finished this game at least four times since I've had it.
Batman: Arkham City - While Arkham Asylum was more of a game changer and had that "wow" factor as it was so different from anything else, Arkham City took everything good and bad about Asylum and improved upon it. Not just an excellent Batman story, but an excellent game that actually makes you feel like you imagine Batman would.
Dragon Age Origins - I know this game has it's detractors, and some might find the gameplay to be uninspiring, but tbh this game was, for me, the game that made me love Bioware. Mass Effect 1 was good, but this... This was something else. Using old themes without making them boring; adding in little quirks here and there to fill out the game (cinematic kills for example), and then making the game actually allow you to be tactical in how you played it. I can't stress how much I loved this game.
Mass Effect 3 - Not as character driven as ME2, the game still has some exceptional plot points. A great story, some wonderful level design, and the constant feeling that if you were in the middle of an intergalactic war, this was what it would feel like. It's hard to make you feel that sense of urgency and at the same time make it enjoyable, but the game did it somewhat flawlessly.
Those are the ones that come to mind for now...