1. Demon's Souls- as far as pure gameplay, nothing else this generation comes close to matching Demon's Souls. It is also the game that made me realize games do not need a great story in order to be great. Demon's Souls places all its cards in its gameplay, and it excels at it. The game is driven by challenge and accomplishment rather than story, and I must say it completely changed how I assess video games.
2. Bioshock- almost in direct opposition to Demon's Souls, I love Bioshock for its story-telling mechanics. While games are emphasizing story more and more, I feel the vast majority of games don't benefit from it. Story and cinematic gameplay slow games to a crawl at certain points, and I feel many games are becoming an uncoordinated mess because of it. I come to a game for the action, and I want the action to hit hard and fast. I don't want to be forced to walk while my squad mates talk or be forced to watch frequent cinematics. The reason I like Bioshock is that it takes a stellar story and crafts it into the game in a streamlined manner. It does this by telling the story through audio logs and the surrounding environment. There are very few points where the game slows down, and there is a great story if you are willing to look into it, but it does not force the story onto you. Factor in an unparalled atmosphere and varied gameplay, and you have my second favorite game this generation.
3. LittleBigPlanet 2- I almost have to put this game in here because of the online component alone. Without the online community, the game would be good but not exceptional. Luckily, the online community is great and consistently puts out some amazing work.
4. God of War III- I can't say much else besides this game consistently had me picking my jaw up off the floor.
5. Deus Ex: Human Revolution- The main reason I like this game is it shows how a shooter can still be well designed. It takes a genre that is stuck in a major innovation crisis and show how to make a quality title by exphasizing strategy and gameplay variety rather than just throwing an endless stream of enemies down a cooridor (I'm staring directly at Mass Effect).