Hrm...of the ones I have beaten (see below):
Kingdom Hearts II was the easiest.
Final Fantasy IV was the hardest.

Of the ones I have simply tried, Dirge of Cerberus seems to be very easy, and FFTactics seems to be very hard.

To all of you who have said that FF VIII is ridiculously easy, I assume it's because you take advantage of the junction system in a way that a casual gamer might not. But then, that's just an assumption. Question: do you all always flee from random battles in FFVIII? Is that one of the major ways to make it easier?