Wait, get rid of Carnival Night Zone? It has one of the best level designs I've seen, and is certainly the best of that era. Everything ties together perfectly, the music, the setpieces, the villains, plus the branching paths that crisscross the whole time, which can seem confusing but there's almost no way to actually get lost, secrets and rooms that feel cohesive. Like, there are rules for where they can go, but the guy putting the level together knew you knew the rules, shaking it up a bit. I kept it off my list because Sonic 3 was so short, and something like that were done today, release a short game then the end a year later, both for full price, people would freak right out.