I think Kefka's insanity makes him the evillist villain in the entire series. Here's a whacko who love death, destruction, and Chaos... and gains the ultimate power in the universe.
I would actually say VI is the best... (though IX is still my fave) but, that's probably because VI was my first exposure to the series.
As on the difficulty issue......
FFI: Hardest in the series. Nothing lots of leveling up won't help. (The weenie (Easy) mode in the Origins version doesn't count)
FFII: Easy. There are a couple of tricks for getting your characters really powerful pretty quickly......
FFIII: I actually played very little of this..... I'm planning on buying this for my Famicom in the very near future, I'll tell you what I think.
FFIV: Somewhat challenging, mainly because new characters frequently start out at lower levels. (The US SNES (known as FFIV EASYTYPE in Japan) version does not count)
FFV: Not very difficult. Getting characters leveled up is a bit easier as there are only four throughout the entire game. (Technically five, actually, but the fifth inherits another characters exact stats, so that doesn't count)
FFVI: Again, I don't remember this one being difficult, just stay leveled up.
FFVII: Forgot.
![o_O :eh:](./images/smilies/icon17.gif)
I don't remember this one being very difficult though...
FFVIII: Probably the easiest in the PSOne trilogy....
FFIX: Not very difficult.
FFX: Again, Not very difficult.