Streets Of Rage 2 - The grand champion - all it was missing were the team moves from SoR1, and the planned ability to play Shiva in Versus ode, really
Strider - It was amazing to see Strider Hiryu move in all sorts of inclined surfaces and hanging from stuff, and the whole game was composed of amazing moments. Maskless Hiryu is the best.
Sonic The Hedgehog - A worthy representative of what the Megadrive was capable of. It managed to get a lot of mileage out of simple controls and mechanics, and even if the game was meant to show off speed but got slowed down for the European version, in a couple of cases that made the
music better.
Shadow Dancer - Classic. Simple mechanics supporting amazing set pieces. Who cares if your ninja and his dog aren't looking stealthy when the very first thing you deal with is the whole damn city on fire and cracking in half with earthquakes, not to mention later stuff like the Statue of Liberty level.
Castle Of Illusion Starring Mickey Mouse - Simple, pretty, fun, and the last boss is called Mizrabel, what's not to like?
Street Fighter ll: Special Championship Edition - This one took a lot of time to reach the Megadrive, so it was nice that it basically provided both Champion Edition and Turbo.
Fatal Fury - I enjoyed this while waiting for SF, but it was pretty fun to play with friends as you could use all the bosses in that mode, even Geese, even if sometimes matches degenerated into "slide wars" (mostly using Joe, Duck King and Geese)
Revenge of Shinobi - I still prefer Shadow Dancer in this series, but hey, you fight Spiderman, Batman and Godzilla
Road Rash - I actually don't remember the gameplay differences between RR 1 and 2 that well, but I enjoyed the game and its concept, so mentioning the 1st one by default.
Might And Magic: Gates To Another World - I never got to finish this one, but it still amazes me how detailed the manual was (as in, every map was there), and yet playing through it the world seemed inconceivably large and beyond understanding, even if it wasn't graphically impressive.
Honorable mentions:
Alisia Dragoon - I didn't actually get to play this, but my GF likes it, so mentioning it for her
Quackshot - this looked so damn good
Greendog - neat environments and
incredibly chill music
Michael Jacksons Moonwalker - loved the music, great use of the regular moves to trigger events in the stages, especially when used as alternatives to the game's magic system, which actually consumed your life bar
Micro Machines - I was never much into racing games, but this got to be fun once I got to grips with the controls.