Thank you, that's what I thought. The sonic MEGA collection has the genesis music.
Sonic & Knuckles collection was the one YOU DON'T WANT cause of that music. Though I never heard it until I played a romhack. Doesn't sound bad though, but I do like the original better.
Sonic & Knuckles Collection is a great version. If you don't like the midi soundtrack then just get the SMPSPlay mod to get back the original genesis music (SMPS is the sound driver that Sonic 1-3D use) in fact SMPSplay let's you customize it to use any songs from Sonic 1 through Sonic 3D as well as Genesis versions of the PC tracks. Also liking the PC music is subjective, I personally prefer Carnival Night and Ice cap more in the PC version.