Void Ventus
Sic Parvis Magna
I don't have time to slog through games any more, so less difficult is fine for me.
I can't talk about the other versions of the game, but this version is the shortest FF game I've played so far. Took me around 20 hours, which is definitely short for a main Final Fantasy game. I didn't play The After Years though, but I heard that was trash anyway.