I have only played from FFVII on. However my favorite one is FFXII.

I didn't get the end of VIII at all and if what I think happened happened, then I didn't like the ending.

Personally, I didn't like Cloud because he messed himself up by being the way he was, so that is why I didn't like FFVII as much as other people.

I just didn't really like anything about FFIX because Zidane's tail was too disturbing for me. The only character I liked in the game was Vivi.

FFX- the turn based battles made it too easy for me and I like a challenge, but otherwise it was good.

FFX-2 was pretty much ruined and didn't really hold up to the FF standards. Plus it was really easy to beat.

FFXII- I liked being able to choose the monsters I fought. Ashe was more of a main character than Vaan was. I also liked the license grid and being able to choose the type of weapon I wanted the character to use, not a preset type. Each character holds each type of weapon differently. Had a good story for a lineal story line. Being able to hunt monsters and getting paid for it was a good addition to the game. The game made it feel more like I could choose what happened in the game, although I couldn't.