7 was the most enjoyable for me, however i have never played any of the previous ones. Of the newer ones, 7 is clearly my favorite. Come on, i know Knights of the Round is cheap but it was sure fun killing time raising and developing those chocobos! Can't beat materia either, some of those combos you could come up with are pretty sick (my favorite is attaching an MP recovery to Knights of the Round, so whenever you used KOTR it would essentially recover all of the MP you just used! Also, if you can get two final attacks per person plus two KOTR per person, you can attach a revive and KOTR to final attack - you die, get revived, then blast them again with KOTR, which then recovers your MP lol).
Anyone have any suggestions on which earlier final fantasy to try out! Thanks!