I find it impossible to pick a game, because there's no game that REALLY amazes me, thinking instantly that it's the best. It's why I hope for TimeSplitters 4, and for it to be good. So it may recapture my nsotalgia and I may finally have a favourite game.
So games I respect even if I havent completed:
The Orange Box. Cheap, lots of games, lots of length and replay value.
The Metroid Prime Trilogy. Good games, and I am proud to own the wii trilogy verison even if it has short-comings. And even if only a 12, the most atmospheric games I've played, and the music itself causes panic.
Viewtiful Joe. I love the cool ideas, even if I'm not that good at it or find it that entertaining.
Dead Rising poses a fun idea. I don't particularly like the characters, but I have enjoyed the sequels CASE games, and I may ge the full game at some point.
No More Heroes. Again another thing I like for being different. I don't mind that the sequel is different, but I wish it had the old camera control, and it told us at least the opponents names before I kill them. I like the beginning of the second one more, but it slowed down after that, and I wish ranked battles gave you money.
And ofcourse, the TimeSplitters games, even though I've never played the first one, and the second seems a bit innaccessable to me now. I hope for downloadable versions of these games to come out.