I liked both VI and VII, although I honestly can't remember what I thought of VI the first time I played it--it's just too long ago.
For me, FF VIII was the real implausible, this-is-crap, throw-the-controller-at-the-TV game. I'm sorry, but you can't have a character who is supposed to be a super-competent mercenary bug out in the middle of an assassination mission to act like a Typical Teenager and expect the game to be treated seriously--I don't care how old she's supposed to be. If any significant fraction of SeeDs were like Quistis, no one would have hired them, and without the SeeD/Garden system, the world-building disintegrates completely. And that's without taking into account the ridiculous coincidence on which much of the plot hinged, or the fact that all of the characters were either stupid or obnoxious. A slightly unusual combat/magic system wasn't even nearly enough to save this dog. It makes X-2 (which wasn't very good either) look like a work of genius by comparison.
::deep breaths:: Just had to get that one off my chest.