This is the topic for Sonic CD and it's Japanese & United States Soundtrack.
The US and Japan releases had different soundtracks? Thats interesting. Any idea why?
Also do you have any standout tracks from either that you would recommend? I've always been a fan of the music in the 2D Sonic games.
I was listening to a podcast with Heather Anne Campbell and she mentioned how the music from those games was heavily inspired by this band called Yellow Magic Orchestra. If you haven't heard them before and are a fan of Sonic music, I would highly suggest checking them out.
Apparently SEGA thought American audiences wanted something more atmospheric instead of the funky, sampling house beats the JP track usually had.
Anyway, you want standouts? On Japanese side, foremost Stardust Speedway (Bad Future). Quintessential Sonic CD and basically became the theme for Metal Sonic, but besides that the Present version is a good shuffle that remixes the game's main theme, which makes sense given that it was originally the last zone. Palmtree Panic (Good Future) is a nice filler song for roleplaying a gameshow host. Collision Chaos (Present) is another good shuffle.
On the American side, to keep up the theme of most famous first, opener Sonic Boom is probably one of the most famous songs in the series, even getting remixed around the time of Generations (Crush 40 and Cash Cash). Beyond that, though, Tidal Tempest is a bop (then again the entire zone is flow as Hell, and meshes beautifully with the JP tracks: (See: this)). Same exact thing can be said about Wacky Workbench, down to "it remixes well with the JP tracks" (See: This). Quartz Quadrant is also pretty great. While I like the piano of the JP version, the electric guitar of the US track just fits too damn well with 90s Sonic.
Also, the contrast in game over and boss music between regions makes for good memes: