Depending on my mood, I kind of flip flop and can't decide if I like SMW better or Yoshi's Island better. Either way, Yoshi's Island is one of the best 2-D platformers ever made, and still looks impressive to this day. And so many great and subtle ways they used the Super FX chip! I have so many good memories playing this game with my brothers and my college roommate and his wife when we were in college.
I'm getting a little worried, though. We're almost to the end of BaD, and you haven't mentioned the other SNES game that's on my top five favorite games of all time list. You did FF6, but there's one more...