I was going to create a poll with the options for Final Fantasy V, VI, IX, X, XII, but don't know how to.

My theories are that, while VI is oft lauded as an epic masterpiece, which I even agree with, there's a way of critiquing the game to suggest that it is ultimately shallow, bears only the semblance of being comprehensive, has a villain that, despite what is entertaining of this, is a mere caricature of mania, and designed to impress in such a manner that would give Square the competitive edge with which to create Final Fantasy VII.

Final Fantasy VII, though the first video game that I really got into and still one of my favorites, is kind of a glitzy display of graphics that became dated almost instantly and ambitious narrative oeuvre that begins their now longstanding history of nearly wholly incomprehensible plots.

Final Fantasy X is evidently absurd in that three of its leading protagonists wear entirely anachronistic costumes, aside from that, by the end of the game, I began to feel bad for the voice actors who had to recite its script.

Final Fantasy XII begins well, but makes all too obvious of a departure from its narrative around three-fifths of the way through the game. I do understand that they lost their writer midway through its development, but, there is a very clear set-up for an upcoming war between Rozarria, where you never get to go in the game, and Archades à la The Trojan War Will Not Take Place, whose entry into after a sweeping journey that culminates in an underground sanctum is entirely botched by that you have to play through a classist sidequest with the game's representation of a "guttersnipe", Jules.

My theory is that IX ought to be the canonical answer to this question. Since there is no poll, you can say that it was any of the games in the series, though.