SNES! never owned a genesis so im a little biased. i did have some experience with it when i was a kid but i still always preferred the SNES, still have my original console!
one memory i had was that my buddy had a genesis, and i remember playing MK1, and it had the infamous blood code and the better fatalities, so with that game at least it was better, the only gripe i had with it was the shitty graphics, the SNES was superior (closer to arcade) in that respect but lacked in other areas.