Off the top of my head, in no specific order, these are all my favorite game soundtracks...
- Donkey Kong Country 2 - Dave Wise really knew how to work that sound chip on the SNES, even better than Nobuo Uematsu could. Before I discovered the wonders of SPC, I would go to the bramble levels to just stand there and listen to the music.
- Final Fantasy 7 - Hell, I can sing along to One Winged Angel. Ultimate geekery at work here.
- Earthbound (or as the Japanese like to call it, Mother 2) - The ending music brought a tear to my eye, and the battle tunes were awesome.
- GTA Vice City - It's still a soundtrack even if the music wasn't originally composed for VC. Nyo. Great oldies ahoy!
- Sonic Advance 3 - Specifically Cyber Track, Chaos Angel, and the final final boss music.
- Sonic CD, Japan and US - New music for the US release just means more music for us, and both soundtracks are equal in awesomeness.
A few select favorite tunes of mine...
- Stickerbrush Symphony - That tune that plays in the bramble levels of DKC2. Easily first place on my list of kickass video game music.
- Rusty Ruin act 2 - In Sonic 3D Saturn/PC version.
- Stardust Speedway Bad Future - From the Sonic CD US soundtrack.