I'm always game for some Final Fantasy nostalgia. Even though I've only played these ones...
VII - Only played it for a few hours, many years after it's release. Think...maybe...2008. Even as someone who appreciates old school gaming, it's hard to look past the graphics. One of those early attempts at 3D that's aged horribly. I can't wait for the remake though. I can definitely see why it was so revolutionary.
IX - Unlike VII, I played this nearer to when it was released. Incredible game. Loved everything about it, the characters, the setting, the dialogue and of course, the music. One of my favourite games ever. It was first introduction to the series and for me it really nails the "fantasy" element. Last of it's kind in a way.
X and X-2 - I like the world of X and X-2 more than any other. Something about it reels me in. And unlike some I actually like Tidus, and the Charlie's Angels sequel. Still think IX has the best music throughout, but To Zanarkand is the best piece of music from any game I've ever played.
XII - Loved this one since it's release. It's battle system is so good that it's the only one I'll likely go back and play again. I just can't be dealing with random battles anymore. Great settings, underrated soundtrack and a few memorable characters are unfortunately let down by a storyline which I understood less than the second season of True Detective.