FF 1 & 2: Get on GBA. I had fun with this one. Played the hell out of it. FF1’s made super easy, while FF2 is the least sadistic here. Loved playing FF2 on this one.
FFIII: Hit or miss. Actually, I enjoyed the NES version better than I did the DS version. It’s not a bad game, but it really hasn’t aged that well, and doesn’t have much of a story. Still one of my favorites regardless.
FFIV: I’d get the orginal or GBA version. For whatever reason, I never could finish the DS version. Definitely recommended as per stated above.
FFV: GBA is the best version here. The best of the FF ports. Think FFIII, but better in quite a few ways. I’d recommend after you’ve played some of the others.
FFVI: I can’t say anything about this game that hasn’t already been said. Try and play on an emulator I suppose for best results. Recommended.
FFVII: Play it. It really is a great game despite the Lego-looking characters and graphics.
FFVIII: Very hit or miss. It’s not really bad, but the whole Draw/Junction system is really awkward compared to other FF games.
FFIX: Lots of fun. Won’t elaborate, but play it when you get a chance. Good nostalgia if you’ve played some of the other games beforehand.
FFX: This is actually quite fun to play, and most everyone else thinks so too. Sphere grid system kinda borrows from FF2 a little, but makes it work. Recommended.
FFXII: Hit or miss. I can’t really recommend it. The story pacing is very SLOW, and it really doesn’t feel like you’re playing the game at all once you got the Gambit system figured out. That and the License board is stupid.
FF Tactics Advance: GBA FFT game. It’s a pretty good game, but it totally lacks any real challenge as opposed to FFT.
FFTA 2: DS FFT game. Read above. It’s FFTA with FFXII elements.
You did good getting FFX, and while the KH series isn’t technically FF, they’re great games also.