FF7 is the best for me, since the FF world were opened for u to explore and a lot of submission too, driving the airship flying around is always better than just clicking a spot on the screen and "boom" u r there. This is what i dislike about the FFX and X-2.

The appearance of Cloud in the Kingdom Hearts series and also the Advent Children movie just make him look more cool (especially the KH2 where u get to c the fighting screen of Cloud and Sephiroth). Tifa is also very cute.

FF7 > FF9 > FF8 > FF10 > FFX-2 (for 3D Final Fantasy Series only)