If I did a quick rundown on SF music...
SFII: So good. You got stuff that are classics, and also from Yoko Shimomura that does Square stuff now lol
SFA2: The music around this time and VS series are so good. Good remixes and a ton of nostalgia for the arcade sound this era
SFA3: The character themes sound more like BG themes if that makes sense. They're less defining, and not quite for me
SFEX: I can't remember the themes off the top of my head. No nostalgia for these, but they're really good
SF3: There are actually some that I like in FG/2I over 3S. Yang's 2I is better than 3S, imo. Ibuki's also. FG and 2I sounded very Darkstalkers-ish though. So I think 3S really did a good job breaking into its own style. The only thing I wished was that they didn't try to do it by stages. This made characters end up sharing themes, but oh well.
SF4: There's definitely some good songs, but there's a lot that are just mediocre to me. The problem is you rarely see these songs because the cast is so huge so you end up missing what some of the new themes are. That and most tourney streams end up on Training Stage.
I'd say I'm the most attached to Alpha 2 though. I played fighters a ton around that time, so hearing that CPS2 sound is certainly quite nostalgic.
SF5 is good so far on music. Some I don't really like such as Laura, and some stage themes are just ok or bad. Brazil has a pretty good stage theme though and some of the character themes are better remixes than 4's imo.