1. Super Smash Bros. Brawl - it's given me the most enjoyment. 1200 hours to be exact. And also because Snake's in it and it's his best selling game. XD
2. Super Mario Galaxy - not much to say about this game beside that it's one of the best games ever and it's got awesome music.
3. Metal Gear Solid 4 - the end fight is one of the best fights ever.
I'll probably add Monster Hunter 3 when I complete it because it's that good.