According to most people that haven't played VI: Best FF. According to most people that haven't played Chrono Trigger: Best RPG. According to me: the 2nd best FF.
Final Fantasy VII was the first FF for most people, and immediatly became everyones favorite, wich is logical since the quality was going down with each part, but enough about that, back the VII. In FFVII the battle system is this time based around Materia, by equiping it in the slots in your weapon you gain magic or skills. The materia system is the best system used in the FF series, since it was easy, but you still had to think about what to equip to who. The music is the best in the entire series, even better then that of VI. The timing for almost everything is perfect, and the story is great. However the game is sometimes a bit too slow, and the game is very long.
Final Fantasy VII is not the best FF, but it is a really good one.