When you say "Dracula X" I always think of the SNES version, if you said "Rondo of Blood" then it would probably be obvious to everyone that you're talking about the PCE version...
Other than that, yeah, this is pretty much the best Castlevania game, one of the best on the PC engine without a doubt (although, as a fan of Fighting games, I like Asuka 120% and Street Fighter II more)
I used to like Super Castlevania IV better, but after re-playing Rondo of Blood I just couldn't lie to myself anymore, it's the best bar-none, the level design is just perfect, the branching paths add loads of replay-value and the graphics and sound are just amazing!
Personally though, I like the background art and the music better in the SNES version (Yes, I like SNES sound better than CD sound), but the PCE still has better animation and an overall better presentation with the cutscenes and all, so I could give the edge to either one...
Yeah, I know the SNES version is overall the inferior version, I won't argue with that, but that one was my first Castlevania game, I'm very nostalgic towards it, and even though Rondo wipes the floor with it I still love it a lot!