Megadrive sound is very ugly. It sounds like a crazy atari st in steroids.. Just music maestros made good tunes for this console: JesperKyd in Subterrainia, and Tim Follin in the unreleased TimeTrax. Follin probably is the best musician of every format available.
SNES sounds rather good, I love this tune:
[ Show youtube player ]
the tune is progressing without hurry, then at 1:15 its simply great!!
much richer than anything a Megadrive may do.
anyway, Amiga has better tracks than both consoles together.