I chose the classics, for two main reasons: I'm the most familiar with it, and also, the tracks were just the most memorable to me. I still remember buying Sonic Mega Collection on Gamecube for the first time, being able to hear these chiptunes in their most cleanest form yet at the time (besides Sonic Jam, which came quite a few years before that, but I digress). I also remember purchasing Sonic Gems Collection for Gamecube, and hearing the amazing musical tracks of Sonic CD, Sonic The Fighters, and Sonic R (along with some rather tasty Vectorman 1&2 tracks). The most notable of all these of course, was Sonic CD. The music, while nowhere near as successful as the overseas tracks (which I didn't even know existed at the time!), were still catchy as hell, and I enjoyed the ever-living crap out of it.
Granted, Sonic CD isn't my favorite Sonic game by far (that little spot belongs to Sonic 2 still. Sorry SEGA, Sonic Colors didn't win me over that easilly, regardless of it's music rivalling Sonic 2's), but if there's one thing about that game I'll always agree with someone on, it's how good the soundtrack was. I purchased Christian Whitehead's version of Sonic CD on Xbox Live a few months back, and I'll admit, listening to the overseas tracks felt much more natural to me, but at the same time? After playing the US edition, I just felt like the music was replaced (can't be helped I'm afraid). I suppose it all depends on where you live though. Say if I lived in Japan? I'd be the exact opposite right now! (On a small side-note, one thing I DID love about Whitehead's Sonic CD the MOST, was that it had the Sonic 2 Spindash, and the ability to play as Tails. F*** YEAH!)
As for the more modern titles? Listen, I've downloaded TONS of Sonic music into my computer. I have so many Sonic soundtracks, and songs, it's not even funny. I'm a Sonic music floozy: You give me a Sonic track? I'll most likely know it by heart. That's how obsessed with Sonic's music I am. Call me weird and odd for that, but it's the truth. XD Anyways! Just know this: I picked the classics, but in the end, ALL Sonic music is amazing....(except for that Modern City Escape track in Sonic Generations. Jesus Christ, what the hell WAS that?!)