I believe The Beatles: Rock Band came the closest to being perfect. Eveything about that game was just beautifully done and the only things missing was Pro Drums, an option for Keys, and a few more Beatle songs (Hey Jude, Strawberry Fields Forever, Yesterday etc. etc.)
CoD 4 & 5 feels like the purest Infinity Ward and Treyarch experiences, Cod 4 set the standards in multiplayer shooters and 5 had zombies, not to mention the story missions are fun. BF2 was also the most fun multiplayer shooter for me when that came out. Thief, Deus Ex, Quake 3, Baldur’s gate 2, and Systemshock 2 are also some games I can’t really find anything bad about.