Im curious which soundtrack people prefer. I love VI, but VI is also my favorite game, so maybe that has something to do with it, or vice versa.
I havent even played VIII yet outside a cursory look.

I think 6 has my favorite sound track of those three.

I actually enjoy VIII's soundtrack quite a bit, especially these:

https://youtu.be/LqbNkCGy6j4 A haunting tune

https://youtu.be/IjQZz4I5Y7E An almost dream-like, wandering melody

VII is by far my prefered M&M, I like its music but I can say, in fact, few tracks are really that good... However, none are bad.

Are musics of others M&M from Paul Romero too?

The ambient sounds in MMVI are great. The werewolves den is like a kid's haunted house.

MM6 is best. Very atmospherical and great tracks in many zones, especially late game zones like Dragonsand and also White Cap. Town music in New Sorpigal is also simply iconic.

MM8 is also really good, especially in nautical/coastal zones, the planes (water and air especially) and Shadowspire.

MM7 is "meh". Very forgettable and uninteresting for the most part. Bracada and Celeste (including the dungeons there) have some good tracks iirc. But then again: MM7 is a very "meh" game in itself according to what seems like me alone, so I might be biased against it.

Yes they are, with some other artist labeled along side him.