I think FF2's the hardest, mainly because I didn't know how to pace myself. When I'd bust my butt trying to get enough money for weapons in one town, there'd be weapons in the next town that I was probably expected to have at that point that were about twice as good.

The main part of FFX is the easiest, because any roadblocks can be overcome just by being cheap. If you want to do the extra stuff, that's quite a bit harder. The enemies in the Monster Arena are hard, so you have to make it even harder on yourself by doing tedious stuff until you can beat them.