I've heard III is the best due to the multiple characters (& paths?) and basically taking the first game's formula & making it better.
Simon's Quest is considered the "worst" of the NES trilogy due to how different it was.
There's no consensus on which is the best. I think 4 is the best, due to its tight level design. Some people prefer Rondo of Blood, as well
I think castlevania chronicles is a port of the sharp x8600 version which was a remake of the original.
Having played both castlevania chronicles and super castlevania IV, both of which are remakes of the first castlevania, would tell you to play super if you had to play one.
4 is not a remake of the first game. Yes, it has the same story, but the levels, enemies, mechanics, music, etc. are all different. Just like how The Adventure ReBirth has pretty much nothing in common with the GB game The Castlevania Adventure.