Both soundtracks are excellent, but JJ2's songs have always been more interesting to listen to and sound more inspired, personally. But then, I'm biased thanks to Tyrian anyway.

Oh, and in response to the comment about the number of remixes, it is always easier to remix a song that is technically simple than one that is highly complex. There's a reason why you see so many mixes from older games on sites like OCR, even though new games have excellent soundtracks.