FFI: Merely a means of moving the game forward. The main characters do not speak.
FFII: A step up from FFI, but still nothing special. Think of it as FFVII-lite without the memorable characters.
FFIII: The best of the first three games, but not by much.
FFIV: Groundbreaking back in its day, but still fairly sharp now. The Final Fantasy Chronicles translation is my favorite.
FFV: A fairly generic story with a couple of really incredible moments. But stay away from the Final Fantasy Anthology translation.
FFVIII: You either love Squall or you hate him. With that in mind, they really did a great job on making this a huge, far-reaching story that unfortunately misses a step about an hour before the end of the game. The cinemas are fantastic and the translation is much better than in FFVII, though the characters are undeniably Japanese creations.
FFIX: The longer you wait to play it, the more you'll appreciate the story. The game was generally more fan service than anything else.
FFX: Not my favorite game in the series, but the only one I literally couldn't put down. I plowed through it in eight days and loved every second. The voice acting is shaky, but it's a great story, and the soundtrack really accentuates it.
FFXI: Nobody's going to list this one, but I'm going to rate it anyway.
- Main Quest: ridiculously cookie-cutter
- Rise of the Zilart: not necessarily as cookie-cutter, but too quick to be interesting
- Chains of Promathia: sensational
- Treasures of Aht Urghan: funny, but nowhere near as deep as its predecessor
- Wings of the Goddess: incomplete
FFXII: I'm actually only halfway through this one. If you can ignore Vaan and Penelo, this is a great set of characters and a decent story. Balthier is frickin' awesome.
Final Fantasy Tactics: If we have to name one "goofy" spin-off, let it be this one. The "War of the Lions" translation clarifies what was always an incredible (but poorly translated) storyline that deals with conspiracy and religion in a way that few games can. Don't miss this one.