#1 - Castlevania III
The gameplay is just like Cv1, but with a lot more variety. Controls are tight, the only exception being Grant's wall-climbing ability (I could never get that to work perfectly). I loved the multiple paths, and even though some of the boss fights appeared multiple times (the coffin bosses) it had enough original boss fights to make it a non-issue imo. As always the music was great, but not particularly better than it's predecessors. I loved the fact that the multiple playable characters allowed for different strategies to be used in how one got from point A to B and during boss fights.
Been doing some pixel art in my spare time, and it's really given me an appreciation for what the designers were able to accomplish with what little they had. Almost minimalistic.
#2 - Castlevania
Great little game that still stands the test of time. My only gripe is that some of the bosses are nigh impossible to beat w/o using the cheap holywater tactic (Frankenstein, Reaper). Yes, I have beaten them w/o using holywater, but it's a pain in the ass, and largely based on luck. One thing I do love though, is that it can be played through in one sitting.
#3 - Castlevania II
Cv2 is a low point in the series for me. I think it had a lot going for it, it just wasn't properly executed. What really killed it (besides the crappy translation), was the almost complete lack of boss fights. There are what, like 3 bosses in the game, Dracula included, 2 of them you can just walk right past, and all of them are ridiculously easy. It's like Konami read some of the complaints about the difficulty in Cv1, and decided to go in the exact opposite direction. The only high points in this game for me is the music and the flame whip.