Heres a list of some favorites:

Imperfect perfection: Morrowind

Perfect perfection: Starcraft Brood War

Objective perfection: Plants vs Zombies

Subjective perfection: Knights of the Old Republic

Perfect for its time: Gauntlet IV

Perfect timeless: Sonic 2

Perfect for its genre: LOZ Minish Cap

Perfect All-in-one: Shenmue II