I had to make a decision between Half-Life 2, Metroid Prime 2 and Metal Gear Solid 3. I went with MGS3 for now. I tend to play the living out of those games for about a month on all the difficulty levels and stuff so I went with that. On top of that I already got Halo 2 so FPS action is taken care of(even though the single player is a sorry excuse for a game).