Being a huge Doom fan, i played most of ports out there so here is my opinion about the sound/music of each port.
PC - It depends on the audio card really...
Jaguar - No music so nothing to say here.
32 X - Pretty bad quality overall.
SNES - I was surprised with the music quality on this one. Although there are tons of missing effects due to lag that bring the audio experience down.
GBA - Bad quality, only a little better than 32X i guess. The problem is that they messed with the compositions, most of them don't sound right, they have missing parts etc.
PS1/N64 - Quite different approach. They changed the music with some atmospheric ambiance which is quite good. Although i admit that i'm very nostalgic about the music so i prefer it.
Saturn - Haven't played it.
3DO - Definitely the worst port. Really BAD frame rate here. Its the only port, however, that sounds like they used real instruments for the music. Its basically the same compositions with some great instrumentation. In redbook audio quality.
About Castlevania.
Its very difficult to rate the music in this series because almost every game has amazing compositions. Its not about the quality of the sound as some of the best tunes come from the weaker audio hardware versions. My personal favorites are Michiru Yamane's compositions in Portrait of Ruin, Order of Ecclesia and of course SOTN which has classic compositions but i don't really like the audio quality, some great tunes sound weak, like Tragic Prince for instance. I'd love to hear a remastered version.