OK, I just beat Super Castlevania IV and I gotta say that was one awesome game. I wouldn't say it's better than Castlevania III (relative time period considered) but I definitely liked the ability to swing from hooks and the insane amount of control over the whip you get. Too bad that's not in any of the other games to the same degree. I was sort of disappointed that...
Spoiler:
Dracula didn't turn into a giant demon at the end...
but he was hard enough anyway