How could you make this poll and not include Final Fantasy VI, the best in the whole damn series? I'm serious, best characters, best villain who's actually competent, best heart-touching scene that every game since has tried to re-capture and fail miserably at (Opera Scene > Eyes On Me, you fucking know it don't try to deny it), it's just...best. Anything I don't like can come down to nitpicks, like how the map is barely visible when you're riding on a chocobo and learning magic dtakes a little too long at times, but again, these are small gripes that can be reduced to nit-picking instead of full-on complaining.
As for who's actually in there...
FFVIII: Story makes no sense, characters are unlikeable jerks, hyperactive half-monkeys or complete dingbats, Drawing magic is tedious and annoying (yes, I know there's other ways to get magic but it's still tedious busywork), using magic is actually a BAD thing considering it's more useful junctioning it to your stats, card-battle game is annoying.
FFX-2: Obvious shameful sequel of a decent game that didn't need a sequel (FFX wrapped up everything nicely, I thought), class-grinding is tedious and annoying, Job Grid (or whatever it's called, I forget) was annoying and confusing since you could only switch to a few jobs instead of any of them, mini-games are annoying.
FFXI: Okay, this one I haven't actually played, but I know enough. You don't start with all the classes unlocked, multiclassing seems complicated, it takes forever to get a damn chocobo and the high-end content literally takes FOREVER AND A DAY to complete and resemble endurance tests of attrition than tests of skill.
FFXII: Eh, I've heard pretty negative things but since FFX-2 left a bad taste in my mouth, I gave this one a pass.
FFCC: The art style really doesn't work for me, and it seems more reminiscent of Diablo II with a nice big scoop of Phantasy Star Online than a step forward in the Final Fantasy entries.
Bottom line, this poll should've included all the main Final Fantasy games (disregarding spinoff series) and that's it. So my vote ACTUALLY goes to Final Fantasy VI.