Castlevania III is very big game, has multiple Characters, branching paths, and graphics wise the best looking. It is balls hard.
Hot take: Castlevania I is better. I just have more fun playing it.
Other than Castlevania, I'd suggest DuckTales, BuckyO Hare, Mega Man 2, and Felix the Cat.
If you want to get into Homebrew platformers: Nebs N Debs and Project Blue (which is on Kickstarter right now).