There's a ton of music that I like the most in both classic and modern.
On Classic my favorite is Stardust Speedway Good Future from Sonic CD (The JP/EU ver.)
On Modern my favorite is Eggmanland Night version of Sonic Unleashed.
There's a lot of really good Sonic music out there. But the two official tracks that first come to mind are Hydrocity Act 2 and Live and Learn. I just enjoy chiptunes and really cheesy butt-rock of the Adventure era games I suppose!
infinte , fist bump , live and learn , sonic 06 main them (in his world) , i'm all of them (shadow the hedgehog) , city escape , green hill (sonic generations : modern and classic , mania ) ....... mosr of all :)