OK, I have been on a major Final Fantasy kick recently. Awesome, right? Well, I have finally realized something: Why I do not like Final Fantasy IX. It is actually pretty simple: I cannot related to any of the characters. In 5, I loved the idea of the adventurer thrown into a random conflict. The cast was interesting, simple, and the world(s) were fun to be in. In 6, well, I love the whole magic concept, and how the Gestal empire was using it as a weapon, so the world was great. I liked all the characters, and really felt sympathy for Terra and her personal conflicts. She seemed just genuinely likable, and the way the story spread across so many people was amazing.
Then comes 7 and 8. Both Cloud and Squall I felt very similar to, in their personalities and internal conflicts. Zach as well, as I play Crisis Core now, I can connect with pretty well. As for Aeris, well, I have a friend in real life who is nearly identical to her. More than enough said on that one. 
As for the worlds, I have to say, 7′s was just an amazing fusion of magic and machine, and 8 had some of the best concept behind it I had ever seen. This all, of course, was a decade or more ago.
Then comes 9. A call back to the originals. Now, I love that idea, and thought the gameplay was fun, but the story was just, well, pretty boring. I found myself trying to play the game just to get it over with. I never did finish it, as the difficulty just made me not care anymore. I got about to the Gulug stone section, and that was it.
As for the world, it was kinda nice, but it seemed rather random. As for the cast, I could not relate to a single one of them, and they all felt stock and recycled from other concepts: nothing that felt real. I had nothing in commmon with any of them, and so, honestly, couldn’t give a shit less about their conflict. Unlike 5-8, and 10, I simply did not have any reason to want to play the game.
On the topic of 10, when you combine a “dead city” with so much heavy magic, asian style influinces to the world, and oddly, just the overall morbiness of their world, it really struck with me. So, well, there ya go. 10 was alright in my book, and I completed it.
I really don’t care to much for FF4 or earlier. Nice stories and all, but the play style, even when revived, would just turn me off, and while I like what I do know about some characters (from Dissidia), I really have no interest in playing those games anytime soon, if ever.
As for 12, well, meh.. Ivalice should stay the fuck out of the core FF series. 11 can go directly to hell, and 13, well, I am interested, but only slightly. At this point, I don’t even consider them final fantasies, as Sakaguchi is no longer with the company.
Those are just my thoughts. Outside of 11, I think they are all good games, in their own rights, but to me, like everyone who plays them, there is a certain point where it stops being a game and becomes an experience; where you arent just a guy with a controller, oh no. You feel for the cast, and in the end, for the hours you are playing, you become Cloud, Squall, Terra, Bartz, and all the other random people whos story you are now so deeply involved in.