I'm kinda with you daschrier, on FF13. It's by no means my favorite in the series, but it was fun. I think it was far less linear FEELING than FF10, which tells you at the beginning of the game exactly where you're going and gives you an idea of how long the game is, at least FFXIII keeps you on your toes. The battle system was great, and I actually really liked the characters, and at least the bits of personal dialog when they were there. The only thing that blasts it is the fucking story. What a POS! And honestly, the whole "make me go back and read journal entries to even know what the fuck is going on" thing was absolutely rediculous! I often complain about bad story telling, but this is one of the first times that bad story telling actually went as far as to impede my understanding of the story. That's actually probably my biggest complaint, even more than the quality of the story itself, the lack of attention put into actually explaining what the fuck is going on.
FF12 is just fine. I recently replayed about the first 1/2, and I quite enjoyed it. It didn't make me go "squee!" but it was an interesting experience. My biggest complaint is that lack of character that the title had: bland environments, lack of emotional connection with characters, just lack of heart all around. I found the environments to be status-quo at best, and very obvious. Even though it was far more open-ended than FF13, I found myself just walking in straight lines anyway, because there was no real joy in exploring those areas. It's probably my least favorite soundtrack in the series.
FFX. Honestly, I find it a bit overrated. I do think that it has one of the best plots in the series, and it uses some interesting storytelling devices in telling them. But the experience is marred by what I feel is the weakest cast in the series since FFV, and TOTAL linearity. Not only is it linear, but except for one deviation, it tells you exactly where you are going to be going at every step along the way. It should have been called "Final Fantasy: The Progress Bar", because that's basically what it is, You head north from one end of a continent to the other, and the game ends it's final phase when you reach Zanarkand. I don't know about most people, but I really like my surprises: good plot twists, and not knowing where it is that I'm going to need to go until shortly before hand. So, good visuals, great plot, terrible cast, abysmal exploration.
FFIX - This ties with FFVI as what I believe to be the most solid entry in the series. There's little to hate about it, and IMO, a lot to love. It encapsulates everything that a traditional Final Fantasy game should be, and does it with a child-like sense of wonder in a genre that was rapidly falling into angsty ultra-realism. One of the best casts of characters in the series, great locales, fun dialog, lots of heart and emotion, great plot that keeps you guessing and goes places you would never expect it to. Also, being the last Final Fantasy with an overworld really makes it a bitter-sweet sendoff. Great soundtrack too.
FFVIII - The one I love that everyone loves to hate. I agree that it has a lot of flaws, but for me, the flaws were things that I didn't really mind, and found myself captivated by the rest. I loved the cast, especially Squall and Rinoa (believe it or not), it had amazing locales, an interestingly-different modern-era setting, a deep, unique, and complex skill system (which everyone but me seems to hate), and probably the best visuals of the PS1 era games. It's also my favortie soundtrack in the series. The actual over-arching plot kinda sucks, but so little emotional effort is actually spent on it, that I really don't mind, I saw it as a wonderful story about a young man coming to terms with his limitations, regardless of the subpar save-the-world over-arching story.
FFVII - FF7 is a great game, but it REALLY has its ups and downs. Many long wonderful sections followed by hours of uneventfull boredom. It has a pretty good overarching story with some great twists, but starts to get a bit hippy-dippy for my tastes at times. My biggest problem with the game is that it constantly feels like it was created by a committee of marketting professionals. Time after time minigames and plot points pop up for no other reason than, "kids these days like..." (motorcycles, snowbording, dick jokes, hard-boiled guys with huge swords, ect.) And seeing at it's reception and sales, it looks like they did they were successfull. That said, it did an amazing job heralding the RPG genre into the 3D age, and standardized many visual elements that were used for years to come. It had a pretty good soundtrack (not quite as good as 6, 8 or 9s), and an engaging story with loads of exploration (me like). The greatest introduction any video game has ever had, IMO. A mixed bag that unquestionably comes out on top, but not without it's drawbacks.
FFVI - Again, one of the most SOLID games in the series, little hate, a lot to love. I've always felt that FFVI was the first truly "modern RPG". It brought the story to a depth and breadth that hasn't really changed much since. Even though it was the last 2D game in the series, it's clear that the game was visualized by the designers in 3-dimensions, sometimes to the point of being rediculously confusing on an outdated engine. The team was obviously ready to work in 3D, but didn't yet have the technology at its disposal. Even so, passion and effort that went into a game of its scope, for the time, is unmatched. Time and time delivering unique and touching moments, great dialog, and a surprisingly human story (the only game in the series with no supernatural plot element). It's the story of one horribley twisted psychopath, and his rise to infinite power. There's no demons, witches, evil spirits, or manevolent aliens calling the shots here, and I really appreciate the starkness of it all. Amazing soundtrack for using the basic sounds available at the time.
FFV - Great skill system, goofy campy story, cliche characters, and fun exploits. FFV often gets shafted for having a bad story. But honestly, people are taking it way too seriously. FFV is a goofy, campy game that knew exactly what it was and didn't try to pretend to be self-important. Where FFIV hides behind a vail of epic stoicism, when it's a ludacrus story about moon-men trying to take over the earth, FFV stands out in the open and says, "I'm corny and I'm proud!" I really appreciate that, actually. The characters, dialog, and story are typical status-quo fare for the era, and nothing to write home about. But it stands as a vehicle to lead the player onto some damned-cool dungeons and areas, a multi-planet-spanning trek the manages to have warewolves, submarines and spaceships all at the same time. It's completely rediculous, but I believe to be wonderfully fun. Lesser appreciated is the standardized interface conventions that made menu navigation a lot more manageable. Equipment and Item shops become infinitely simpler to deal with than FFIV, as did inventory management. And Final Fantasy finally decided, once and for all, how and when save points were going to occur. Where FF4 sheepeshly places them here and there, almost appologetically, FFV makes it clear where save locales are going to occur, making the era of church saving ancient history.
FFIV - I've never played FF3 (except for a few hours of the DS version), so I can't comment greatly on it's progression from previous games, but FF4 obviously did quite a bit to bring the series into the 16-bit era. It was the first game to include story and decent gameplay in the same title. There are a lot of fun elements, but it tends to take itself a bit too seriously at times, for a game that merries status-quo knights and chivelry with loopy stories of moon men and whale-shaped spaceships. It's a game that kills off every character, only to resurrect them 2 hours later, where every villain is simply a puppet of a larger villain (on and on and on), and characters turn from good to evil and back on a whim with little explanation. It's also marred by some substandard interface designs, the lack of progress bars for a time-based battle system, and a rediculously slow battle pace. But that said and done, it does offer many hours of fun entertainment, and I'm sure builds on its predicesor spectacularly.