gunstar heroes is one of the best games I've ever played, I don't care if the Snes could handle it or not, if it was on the Jaguar I'd have bought it soley for that! I voted for the megadrive simply because I found it offered me more at the time. I've always had a fondness of it.
I used to own a SNES and a megadrive but I still own the megadrive (well about 15 of them), I let the SNES slip many years ago which was a shame, I loved a LOT of games on it, just nowhere near the equivalent on the megadrive.
Sales mean nothing when the question is which do you prefer.
Oh and by the way.. on the Mega CD...
Heart Of The Alien was good