what makes an ff great?

There wouldnt be a FF without a storyline, they basically reuse the music and every FF anyway

No, there's only 5 songs that have been re-used more than once, and one is the Chocobo theme which keeps getting re-worked in every game.

i think the storyline is what makes final fantasys so good,and thats why ff7 is my favorite

I would say game play and storyline makes a game great.

More game play than story, because no matter how good a story is, it's often not worth playing if the game sucks.

FF6 easily had the best story and best game play. Every part of that game speaks perfection. Although FF7 is a fun and good game, people calling it the best FF is a bit overated. It just happened to be the first FF that most FF fans played...and that instills bias automatically right there that older FFs couldn't possibly be better. I actually played FF6 AFTER FF7 and found FF6 superior in every way(even graphics). But FF1 was my first FF.

I agree with Dingo, gameplay and story are the most important. You could make a good game with just those, really.