Technically, I never left, haha (since my browser stays open). Actually, I was viewing images from FF7 a few days ago, and one led me here.
Having played 4 through X, X-2, and 12, (and partly through the original and 13), its hard to elevate one above all others. I wasn't allowed to play anything else but Gameboy until my father died, then my mother got a ps2. So i started (the series) out on X, found 7, 8, and Legend of Dragoon in a pawnshop later that year, and continued from there. I found the stories of 4, 7, and 9 to be the most enjoyable, although I did enjoy Kefka quite a bit as well.
5 gets the "best personal story" award and level-up system. I found being able to master a large amount of classes, to be the most fun.... only for it to not mean anything in the face of Exdeath. Why, because I thought "ehh, dont feel like stocking up on Phoenix Down, Red Mage ftw." Ended up running out of phoenix downs, trying to keep the Red Mage alive...and eventually all I had left was Krile. So I kept timing the Jump ability so that she would be in air during the attack until finished.