I - Just a simple turn based classic RPG grind. No real story. Can be fun.
II - The first one with a story, old, but worth your time
III - Haven't played it
IV - A bit tedious, but a classic. Definitely worth playing at least once.
V - Haven't played it
VI - One of the greatest video games ever created. I still listen to the music CDs I have of from this game.
VII - Not very good. Very long. Really crappy first gen playstation graphics when everyone thought going 3d was cool before it stopped looking like crap. Most people played this as their first FF game, and have very rosy glasses when looking back at this game. Kind of like people asking for classic realms for WoW. Things might have been great back then, but really? Things were actually very crappy back then.
VIII - Very bad. Bad magic system, bad characters, bad story, very boring. Kind of like watching a Twilight movie. Complete waste of time.
IX - Back to the classic styles. Good stuff.
X - Some wonky things, but this is where the 3D starts to actually work instead of being in the way. Some voice acting was really great (some was bad) and overall was a good game.
XI - MMO - is it even still running? I hate that they wasted a number on this.
XII - Haven't played it.
XIII - Haven't played it.
XIV - MMO, stick with Warcraft. Lots of negative feedback from this one, like high up executives stepping down over failure.