I did not play most of these games when they first came out, my first final fantasy was 7 so when i played the first ones it was just i had found the dark ages of gaming
ff1: It was a fun game, definitely a time waster but there wasnt that much depth to it
ff2: Liked how the characters actually had personalities but still fairly basic for an rpg
ff3: I only played the ds one and from what i heard it is pretty much a different game but still it was pretty fun, liked the more in depth classes
ff4: This is where things got interesting, had characters with alot more depth and the characters were very creative
ff5: I have not played this one yet
ff6: I have only played about an hour into this one but the most noticeable thing to me is that they call it a "fenix down" in this game
ff7: My first final fantasy games and one of my top but not my number one, this game changed everything though, 3d graphics, and imaginative plot and a great cast of characters
ff8: My personal outcast in the final fantasy series because whenever i play this one i don't feel like im playing final fantasy, otherwise great cast but a weird convoluted plot
ff9: A return to its roots, this game has been a pet peeve of mine because after the first time i beat it, I couldnt return and get past disc one for some reason, otherwise very cool game i liked the whole cast and Vivi was a badass
ff10: This one took a giant leap in terms of graphics and narration, good cast of characters, who didn't like auron? crazy story though
ff11: Never played it because its online
ff12: My current game at the moment, dislike vaan and penelo but otherwise great cast as usual, not that far into the plot yet so i can't say much
ff13: This took graphics even further into realism and completely overhauled the gameplay, the characters in this one were pretty much all whiny bitches except for sazh, and the gamplay was very linear excluding near the endgame
now time for the spin offs
fftactics: This is my all time number one game for final fantasy and non final fantasy games this game had everything, an amazing cast of characters, a great interesting story, fun gameplay, the sprites for each character was detailed and the 3d for the field was just great
ffcrisiscore: zach is awesome and this game was pretty awesome, great graphics for psp, fun gameplay, but we all new how it had to end
ffdissidia: a whole new genre in the series, it was a fighting game that was unlike anything, with intense combat and people flying around willy nill whew it was great but not the best.
and thats pretty much all i can think of off the top of my head