The soundtrack of every Sonic game is among the best in video gaming, in my opinion (except for Sonic 4, because they even found a way to mess THAT up

), so I think you both can argue that each soundtrack is better than the other and get basically nowhere.
Has anyone played the compilation for DS? It's really fun.

I think this is probably fair to say. My favorite is Sonic 2, but that's only because I grew up on it. I'm sure if I played a lot of Sonic 3 when I was younger I'd like that music more (I didn't, since I didn't like it back then either).
Honestly though, me not liking a game that is beloved by all should always be taken with a grain of salt. Here are some other opinions I have that may make people gasp in disbelief:
Castlevania II > Castlevania III (IV beats them both by a mile though)
Majora's Mask > Ocarina (Not as strange)
Pretty much any decent game > Mother Franchise
Mega Man 4 > Mega Man 2+3
Final Fantasy blows with the exception of the first one
Just throwing that out there. My tastes in games can be pretty different, and any time I state them I'm just sharing my opinion, not trying to start trouble

I grew up on Sonic 2, 3 and Knuckles (along with Ristar, which was a freaking badass game), so I know the music in basically every early Sonic title is on even standing, IMO. That's also why going back and playing Sonic 1 frustrates the crap out of me. >.<
As for your other opinions, I never played Castlevania, and never really got into Mega Man (it's a story similar to yours; playing the Gameboy Mega Man 2 and sucked at it, so never played any other ones). I have friends who have a similar opinion of Majora's Mask vs. OoT, and when they bring it up I politely slap them. :P I never got into Majora's Mask tho (the three-day cycle really turned me off, and in my eyes it never lived up to the majesty of OoT), so I guess I need to give it a more fair chance. Never got into Mother and only really played Final Fantasy 7 (not much of it) and 10 (almost beat it), but I liked those games.