Yea I hear ya AndyUK... But it seems (I could be wrong since I'm from Brasil, and haven't been here in the US for that long) that the Megadrive/Genesis just wasn't as popular here as it seemed to be in other regions of the world. In Brasil, Sega always did very well, and there the ratio was 8 out of 10 would have a Megadrive instead of a snes. Games like Sonic there did well to put Sega's console #1. Even Sega Master System was very popular there. That was my first console I ever owned. Several Sega Master System games were made there due to it's popularity. Here in the US most will ask, what's a Master System? They here know more of Gamegear which is the portable version of SMS.
I could never really get into the MD/Genesis somehow. I did notice a lot of games had more creative programming and use of the pallette than the SNES games, but I can't think of one MD game that really entertained me.
I never got into the Megadrive either... everyone always seems to love Sonic games but to me they're just "another platformer"... I'm for Mario... Mario games always seem to have so much more character.
I was thouroughly entertained by many Megadrive games, most games were more fun with 2 player though.
Sonic 1 2 3 & knuckles (sonic 2's 2 player is the best thing ever)
Buck rogers - countdown to doomsday
james pond 2 and 3
micro machines - all (in 96 you can make your own tracks!!!)
toejam and earl (2 player must)
ok i'll stop there.
on the Snes however ive only really enjoyed a few games
Final fantasy 6
yoshi's island (on gba version)
but it's an unfair comparison since i don't own a Snes.