i don't blame people for thinking sonic 2 is a better package than sonic 3/knuckles, and yeah, it's a pretty good game overall, it really kicked classic sonic into high gear, introduced tails, and all of its zones are, at the very least, memorable.
however, i'll always prefer sonic 3 and knuckles because of how it expanded on the sonic formula. every zone smoothly moves into the next via cutscene or just starting exactly where the previous act left off. every act has its own distinct music track to signify the level's changes. the special stages are now hidden around the stage to encourage exploration, as well as the new shield abilities to encourage more exploration, plus giving people a reason to choose sonic.
sonic 3 has an extremely well defined world that you can immediately understand just by looking at it. the levels themselves and the details inside them are the story here. lava reef has the death egg waiting in the background, waiting to be activated again. hidden palace and sky sanctuary feature knuckles putting his and sonic's differences aside for the sake of angel island and the master emerald. there's just so much to unpack, and that's why i love the game as much as i do.
did i mention that the game has great stages i probably didn't the game has great stages