Alright, where to start? (I know I will forget stuff and it makes me angry already lol)
- Sorry to generalize it, but pretty much every Sonic game. I could fangasm over Sonic music all day. Special mentions: Sonic 3: Final Battle, Sonic R: Super Sonic Racing, Sonic 2: Sky Chase Zone &Mystic Cave Zone, Sonic 06: His World & Dreams of an Absolution, Sonic Adventure 2: Live & Learn, etc. This list would probably go on forever.
- Final Fantasy X's OST, special mentions: Suteki Da Ne, Assault, People of the North Pole, Seymour Battle, Otherworld. I like this OST so much because it's really diverse.
- Megaman 2, for obvious reasons. (Not only 2 but on other Soundtracks only like 1 or 2 tracks, so yeah)
- VVVVVV, great Chiptune Soundtrack.
Special mentions: Megaman X, Storm Eagle Mario 64, Dire Dire Docks FFVII Crisis Core, Price of Freedom