Mario Kart 64. There are people on this site that have remixed it many times over. Catchy tunes, many more pleasant ones, and then you have games that will probably be in the furthest parts of the human mind - - like Quest 64.
Although I have made little sense, what I'm trying to say is some ports from one system to another, the original may sound crisp to the systems capabilities while the newer port will most likely sound like warbled shit. I don't think there is a reason for this, but it usually happens when they try to use the same music for two different sound formats.
If you want a prime example, find someone with an SNES emulator and one SEGA Genesis emulator. try to find two separate copies of "Maximum Carnage". Not "Separation Anxiety", the first one for both systems.
Don't play it to be serious, you'll frustrate the fuck out of yourself. Instead, listen to the highs and lows of the pitch in both versions. The SNES version of M.C. sounds fuckin' awesome while the Genesis version sounds like it was horribly dubbed. So there are some ports that'll make you go "Huh?" but it's all in how you take it. Who knows, you can actually pick apart the core tune of the horrible version and probably remix it.