Not to derail the thread, but I agree with Aaron. To a degree it's a matter of personal taste though. But I prefer V to IV, and IX to V etc.
Solution: play them all and decide for yourself!
Ture, I personally like VII, then IV, then IX, then VI, then V, then X, then XII, then VIII, then III, then II, then I. That's the mains series FFs that I've played ordered in the order I like them from best to worst.