>>720011448
Funnily enough, Castlevania 2, arguably. You'll maybe need a guide for figuring out what to do and when, but that aside, I'd say it's easier than its NES brethren, at least. There are times where enemies may more easily whap you around, but Simon can get to being hella resilient, not to mention laurels give you on-demand temporary invincibility.
After Simon's Quest, IV isn't totally a walk in the park, but jump directional control and 8-way whipping loosens things up and is a sort of retelling of 1 on top of that. Rondo of Blood arguably isn't that bad depending on who you ask but I don't know, that game's first stage throws skeleton katanamen at you. Symphony of The Night is a totally different thing from CV1, but it is easy as all hell, if it helps. Most of the metroidvanias afterwards are pretty easy, as well, save for Circle of The Moon and Order of Ecclesia, but Portrait of Ruin is a step below those two while still being a step up from the others.