It seems, my friend, that you and I were never meant to be friends.
I'm throwing in for XIII. Never played XI or XIV, though. Never really even touched the VII Compilation either so I'm kind of out of date.
Explanation: XIII I only ever finished because a) I bought it, and b) it's a numbered Final Fantasy game. It's only the second game in the series that I actually put down and stopped playing for a time during my initial playthrough - briefly during Palompolum, for a week or so during the Chocobo park bit with Sazh, and then almost permanently after the the Fifth Ark part or whatever it was called. After I finished the final boss I was so unimpressed with the ending and the game as a whole that I ended up actually trading it in a few weeks later and I rarely, rarely trade games.
As opposed to most people who disliked the game, I actually liked the combat. Especially when you get free reign over it in chapter 11. The problem is that for me I found very little else to enjoy outside the combat. XIII felt to be like a game about combat that happened to also be an adventure, as opposed to one about an adventure that includes combat as one of its major elements.
EDIT: Overall I'd give the game a 4/10 with at least one of those four points being because of this song and the location that accompanies it: http://www.youtube.com/watch?v=4q3tKL2mRl4