I have to say I found the music for spectro to be much better than MSEP. I know when I first say MSEP in the 70's I thought it was the coolest ever because analog synths were still relatively new and sounded so cool... But honestly music has moved on and listening to them now has a little nostalgia value but it really is kind of like watching a silent film - seem a little cool a few minutes but gets old quick. The last time I pulled out my old record of MSEP I didn't even get through the whole song before it just seemed a bit boring. Spectro on the other hand is a much more rounded work that I could listen to over and over. In fact I could probably use it as background music while I worked and not get tired of it by the end of the day, not something I could ever do with MSEP.
Visually, they are probably tied... bits of both are good visually in a perfect world I would hope they might combine the visuals of both and get Debney to write them new music in the same style as spectro.