I'm pretty sure there's thread like this in the past, which got removed because something like not related to XIV or something.

Anyways...

My main fave is always be FF6. Think the majority who vote FF6 here already said the greatness of that game. My only remark is that FF6 could be considered the "Lord of the Ring" version of FF in term of scale. Remaking this even faithfully will take very huge resource. (I'm excluding that recent smartphone remake, since it's just updating to higher artwork)

And my next fave is FF9, only because the game was meant to capture elements from past FF games which then mixed wonderfully into beautiful brand new story.

And don't get me wrong, I like majority of FF main series. I do regretted that I haven't tasted XIII at all simply because I don't have PS3 and even if I did, wouldn't have the time to play offline games since online drained so much of my energy.

But for my own personal taste, FF7 would be the bottom of the list. Why? FF7 in my own term, is a spoiled child. The spinoffs created after that feels like forced idea that I felt doesn't really do justice to the main stories. And this game is actually the reason why later FF series would spawn their own spinoffs, and even old one like FF4 got similar treatment too. While FF7 itself not really the true pioneer, (since there's old series that also got their own spinoff, namely FF5 which has it's own OVA series that flopped bad) the actual success of FF7 spinoff does sparks future series getting sequels.