I forgot to say that, while playing Assassin's Creed, it made me feel bad that I was not holding the controller when Leonardo asks you to hug him. I missed the button press and I regretted not doing for the rest of the game. Sorry, Leonardo.
Either way, off the top of my head...
1. Dragon Age: Origins
2. Assassin's Creed 2
3. Batman: Arkham Asylum
4. Uncharted 2
5. Shadow Complex
6. Modern Warfare 2
4, 5, and 6 are probably interchangeable. I'm likely forgetting games.
EDIT: 2 and 3 probably can be switched around any given day as well, but I think the gameplay in Batman is a bit too repetitive at times, while Assassin's Creed never lets up.
EDIT: But my God, that mood and setting in Batman is so alive.