Personally, I thought FFX had the best characterization since VI and VII. Admittedly, some of the cast members' distinctive traits are quite annoying, but as human beings, they are believable and solid. Well, except for the one who isn't a human being, but he's a believable and solid blue anthro tribal panther. Plus, the CTB + Sphere Grid system allows for a lot of personal tailoring in the game play. You want seven uber mages, you can do that. You want five physical powerhouses and two healers, you can do that. You want to give no one any stat ups or learned techniques at all, or summonings, or overdrives(FFX version of limits), and still win the game...you can do that too. Also, if you want atmosphere, you get it by the metric ton. Zanarkand, in both forms, should do the trick quite nicely. All in all, the only real downsides are that the voice acting is very bad, and skating down wires from moving airships is impossible.
Its sequel, however, is pure ass and fails on so many levels. The characters are mere shells of their former selves. World-spanning organizations and religions are being led by hipsters. The main threat is, for all intents and purposes, a rusty super robot. And of course there's the so called plot line. Full of stupidity, including trying to make the inhabitants of the FFX planet out to be
*NONSENSICAL SPOILERS*
the ancestors of the Cetra, not by reasonable plot development, but by a single slight reference and a directorial fiat via Ultimania. This is contradicted not only by both core games, VII and X, but external plot related materials as well.
*END NONSENSICAL SPOILERS*
The only good point is the return of the job system, and guess what, they managed to break that as well, with the ultimate character jobs. So yeah, like I said, pure ass.
FFIX is a good game. Unlike many of the recent games, I can't point to something and say "That really sucks." True, Necron does kinda jump out from nowhere, but that isn't so much a plot hole as you'd think. Unfortunately, neither can I point out a particular feature and say "That rules." The closest thing that I'd put to that is the chocobo minigame, and that's not only optional, it's basically there to lead you to the ultimate superboss of the game.
Haven't played XII, and as of right now, have no plans to. Busy with some other stuff. I've heard both good and bad about it, and my only real exposure to it has been videos of challenges and the like. Of course, this has led to a slightly skewed perspective. One in which I don't think much of S-E making a game where you can just set your characters to auto-do-this-and-that, sit back and watch the extended version of Return of the King, and then when you get back to the game you're about to land the death blow on the ultimate superboss.
Superbosses should not work that way. You should actually have to fight them. Of course I have no trouble with setting random encounters with much lower levels than mine to auto-kersplode, it removes the annoyance of random spawning weenies.
Anyway, there's my two cents. Do with them what you will.
~ Sophie