Ok, first up im going to say that it is impossible for there to be a best ff. They are completely different games, saying one is better than the other is like saying that Dumbo is better than the Matrix.....they are completely different so you cant campare. So theres no such thing as the 'best' ff, but of course you can have a fav ff.
Second thing, i agree in most (I SAID MOST) cases that the first ff a person played usually (I SAID USUALLY) ends up being your fav. For me, I played VIII first and I love it so much i could graft it onto my skin for all eternity ..........errr....yeh heheheh