Gameplay wise I feel FFI was easier to get into. While I was able to enjoy FFII after learning the kinks it's not as self-explanatory to me as FFI was and that cost it some big points for me. Obviously, II has the advantage over FFI in story and characters. I think the same could be said of III since everything I heard about it talks about zero characters or anything. I can't rate FFIII beyond that since I haven't played it yet.

I think I would rate FFI just a little bit higher, but FFII is still a good game.