Did I forget something? I know people are going to ask about Baulder's gate. Not in the same class, IMO.
Playlist: Mlb 2K8, Wii Sports, Wii Fit (!!!), Viva Pinata
(You'll notice that ever since I beat Oblivion, I've been more of a "casual gamer". That's Oblivion for you. That's about as hardcore as it gets in the world of one player RPGs.)
What defines a favorite game? These days so many games are so different that comparing a game like Oblivion to a game like Team Fortress 2 seems unfair. So I'm going to give two favorites: favorite Single player and Best Multi Player.
Favorite Single Player: This is a tough one. I would have to give this one to Bioshock. I beat the whole thing only one time and in basically one sitting. It was such an experience that was haunting and enlightening. Runner-Up: Star Wars Knights of the Old Republic 1
Favorite Multi-Player: Another toughy, but it's easier than single player. I'm actually going to differ from what I though earlier today and say World of Warcraft. That game has sucked me in and kept me there for the longest amount of time and offers such an in-depth system of player interaction that I have to give it to it. Runner-Up: Team Fortress 2