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.)
Portal 2 has grown on me more and more over the years. Now when I replay Portal, I’m disappointed that it’s not more like Portal 2. The story, the puzzles, the overall mood, the environmental design, the characters, the damn soundtrack—everything’s just perfect.