Get ready for a freaking huge post, because I love talking about FF games =P
FF1 - The original. Probably a bit too much with the diffuculty curve for new RPers. The newer version on FF: Dawn of Souls is WAY easier and therefore propably more enjoyible from less frustration. It's all about the Red Mage!
FF2 - I don't really suggest it that much. I played it a bit and didn't like how the battle system was as well as the dialogue system. I think it was when they tried to be more like the PC RPGs at that time. Introduction game for the chocobo, I believe.
FF3 - Havent' played it yet
FF4 - The transation from 'ancient' to 'classic' =D Great music, great characters, spiffy story. Battle system still not as free as the later FF games, but if you want old-school, this is the one to go for. Kain pwns. Nuff said.
FF5 - First FF game with the job system, giving oodles of freedom on how you want your party to be like. Really awesome story and battle system (being with jobs, of course). Not as free as FFT, but still interesting. The boss's name could have been better though. Faris is the man! ...sorta.
FF6 - In my opinion, THE greatest FF game in terms of deep storylines, unforgettible characters, and true epicness you can see halfway through the game. Goes back to special original classes, but with the Magicite system, you can learn spells and nudge stat-leveling a bit more than FF4. Sabin + Gengi Glove = da bomb.
FF7 - I know what most of you think of this game. I like it. First FF game to go 3D, so it looks a bit off and such, but being an old-schooler, it's more about actual GAMEPLAY than being flashy. Freaking shallow modern gamers can kiss my butt... Anyway, the story is just a tiny step down from FF6, but this game is uberly great thanks to two things. Materia and minigames. No other FF game has the potencial to make the types of combos you can do with materia, which is really fun for those who like to play around and experiment with abiliites. Also, I just can't get enough of playing both that one motorcyle game and, of course, chocobo racing. Oh, and Cloud is NOT gay! >_<
FF8 - Personally, I didn't like this one one bit. The graphics were buffed up, true, but there were some details I'd prefer left out... like Squall's fuzzy jacket. The GF system was pretty good, but it just went downhill from there. Frustrating weapon upgrading system, annoying spell system, ugly Cid, broken money gaining system, unrealistic love interest, and among other things, the most baffling ending in all RPGs, let along FF games. Also, battle system itself was broken after I found a way to keep Squall attacking continuiously with no chance of the enemy of butting in. ...KH's Leon is better than FF8's Squall >_>
FF9 - Haven't finished it -yet-. Went back to the classic looking style of FF games. A bit blotchy with the graphics, but I say what I say before about that. So far from what I gather, the battle system is a bit downgraded, though I like how you need to hold onto equipment to learn abilities. I'm always a bit happier when they stop power-gamers in their tracks =P But so far, it's a rather decent game. I'm a big fan of Vivi =D
FFX - Great graphics, great story, amazing leveling up system, strategic battle system, fantasic summons, and spiffy weapon modding system. But it was too short, and the last boss was a pushover. *shrug* Still, worth a play, though, as this was a pick-up from going downhill a bit in the FF series. Auron... is... UBER! (if you like the battle system here, also try Lord of the Rings: Third Age for more of that spiffy stuff =P)
FFX2 - My opinion... a blastphamy in FF. It's an actual FF sequal for crying out loud! Also, it's a fan-service game that mixed up FFX with Charlies Angels. It's good for other people, I know, but not for me. Only thing going for it are the involving side quests and minigames.
FFT - PS1 game, but it really is a classic hit. Best for strategy players that likes to think ahead and such. Actually... best for those who like to think a bit -too- much, considering the really heavy and somewhat religious/political-based storyline
A true show of the job system, though. I loved this game. Mustadio is da man!
FFTA - If you like FFT, then try this one on the GBA. Goes about the same, but a lot of the jobs are race-based, and the game concentrates more on accepting missions and such. In the end, though, it became a bit too easy with some of the abiliites you could get and combos of. And I thought it was too short too. Moogles!
FFCC - Haven't played it, but I heard it was really annoying in multiplayer mode. From what I saw, it's less of an RPG and more of an Adventure game, like the Zelda series. I still gotta try it out, though ^_^;;
Kingdom Hearts - Not an actual FF game, but it's half FF and half Disney. Action-RPG. The story is intersting, and it can get preechy at times, but I found the game overall very enjoyible. I'm looking forward tot he sequal which is coming soon =D ...and I'll never look at Goofy and Donald the same way again.
KH:CoM - A GBA game. If you LOVE KH, then try this one out. If not, you might find this a bit more frustation for your troubles. Continues the story... somewhat. You'd have to see for yourself. But it's still an Action-RPG, but with cards thrown in the mix. The thing is, higher-numbered cards can counter what's played there, so you can't just hack and slash your way through like in the original KH. Takes thinking and improvising to survive. Axel is so cool even though he's evil
LEVEL UP ! !Chocobo Racing - Older spinoff game on PS1, I think. It was cute and fun, though I didn't play it enough ^_^;;
Chocobo Dungeon - Never played any of those. Same as Chocobo Racing, being older spinoff games on the PS1, I think.
That's about it for me. Hope my info is useful. Remember, all of this is my own opinion, so if you think differently... I guess we have different opinions. But these are coming from one who played (almost) all these games, and then some =P
~Tek Station