I realize this is going to look like Burninglove listing her fetishes but here it goes:
FF1 - Other than the novelty of being the first one there isn't much to say about this one. It can get EXTREMELY frustrating though. I'm sorry but having to fight the same 2 or 3 enemies everytime you take 3 steps isn't exactly my idea of fun I remember that when I finished it I ended up setting the emulator speed at 200% or something. It probably saved me like +10 hours of just killing the same 2 enemies over and over again. In terms of story I can't really blame it, you could only cram in so much plot in a 1987 NES game.
FF2 - I forgot about 90% of the battle mechanics but I remember it as being somewhat decent in general. Sure at times the story takes itself too seriously but, still, its night and day compared to FF1.
FF3 - Never played this one and from what I've been reading about it having the same encounter rate as FF1 and some ridiculous plot, probably never will.
FF4 - This is where I really started to get into Final Fantasy as a series. Even though they still use crystal faggotry as the backdrop for the plot, the characters themselves - and more importantly - their interactions, are pretty compelling. IMO this is the first real solid FF game to ever be released.
FF5 - More or less the same as FF4. Annoying crystal faggotry as the main plot backdrop but the individual characters are pretty good. The job system is awesome (I know some people are going to disagree with this) and I've always loved how much customization you could get out of it.
FF6 - The best "classic era" Final Fantasy game. The crystal faggotry takes a backseat to an actual, well writen plot. this seems to be the one people seem to disagree the less as being one of the greatest - if not the greatest - game in the franchise. Solid battle system, great music, great graphics.
The only big, glaring flaw this game has is the *SIGHHHH Colosseum... I hate that this is what basically started the trend of having terrible, borderline manic obssesive mini-games in Final Fantasy. I get the japanese love this type of shit but I couldn't hate it more if I tried.
Still, even knowing the Colosseum is a broken mess, FF6 is still not only a fantastic Final Fantasy game, but a fantastic RPG. It would probably be my favorite if it wasn't for...
UH OH! CONTROVERSY AHEAD!
FF7 - Look, I know that some of the people who played the game back in the late 90s grew up to be creepy animu faggots who ended up drawing fanart of Sephiroth fucking Cloud up the ass with a tentacle katana. Yes, we have all seen the terrible fanshit ff7 has sprawled. Yet, at the same time, you can't really blame the game for it.
Its probably the most "Star Wars" FF game in the sense that it starts out throwing you in the middle of the action and once you feel like you've "settled in", it opens up to a much bigger plot. This may be the first (and only) game in the franchise whose characters feel like they have an arc, they start out on point A and end up on point B, unlike the rest of the series where they start at at point A and refuse to move an inch from it (Again, people are going to disagree with this).
My main gripes with this one are, again, the dreadful minigames, but also, the fact that it hasn't aged well at ALL, it had the bad luck to come out during the time when they were still trying to figure out how to model stuff in 3D. If there's a game in the franchise that needed a remake, is this one (yes I'm also a FF7 remake faggot). I know that I'm never going to get a remake, Sakaguchi ain't comming back. SquareEnix realized that the promise of a FF7 remake is what keeps a lot of people from completely forgetting about the series. I guess you could say the same thing about Valve and episode 3, but at least they've been making good games since episode 2 came out (which really says a lot about what type of company SquareEnix is).
I remember reading somewhere that they would only make a FF7 when they felt like the entire series had gone down the drain. Let that sink in.
FF8 - This one is I have the most mixed feelings about. You could say that this is where it all started to go downhill, when they started to pay more attention to how the game looked and sounded instead to the most important thing in the Final Fantasy games, the plot. Aside from the fact that they tried to mix the highschool thing with FF, it doesn't really have much going for it. The love story is bland and cliche at best and it also reeks of Twilight and yes, the junction system being the worst thing ever invented is not an opinion anymore, its a fact. Although this isn't the worst game in the franchise (we'll get there) its still really disappointing.
FF9 - I only recently started playing it and I'm almost at the end. To be honest, aside from the graphics and soundtrack, the plot is pretty stale and it suffers from a lot of kawaii japanese furry shit that just I can't stand (Fuck you Eiko).
FF10 - For me this is the point where the wheels completely came off. You can't listen to that voice acting and tell me that it sounds good, hell, you can't even say that they sound like normal human beings. The plot is so bad that it almost seems like it was on purpose, like SquareEnix was actively trying to troll their own fanbase with this terrible script (Yu Yevon). Again, good graphics and music (and a very good battle system) can't make up for a shitty story. FUCK BLITZBALL!
F11 - I actually played this piece of shit for 2 years straight and like the recent games before it, its the same bulsshit. Good graphics, good music, terrible mind numbing plot. There's almost no exploration and the social aspect of it is pretty horrendous. Trading with other players is a pain in the ass and doing things in a group is almost impossible since the UI is one the worst I have ever seen.
FF12 - This one brings out the hipster in me. I know a lot of people hated it but still, I thought it was enjoyable. For some insane reason SquareEnix realized that their writing skills are dreadful and decided to make a pretty basic story that doesn't get in the way of the gameplay. (Loved the license system). However, IMO, this is was too little too late.
FF13 - At first I thought everyone was exaggerating saying this was the worst FF ever but then... I played the game. There really isn't much to say here that hasn't been said before. Linear, uniteresing and convoluted plot that doesn't make sense even by its own rules, press X to win and all the creepy weird japanese animu shit in it. The game can say that Serah is 18 all it wants, but that there gurl is 14, they designed her character to look 14, and they know it

. So much so that the first thing that I get when I type "Snow and Serah" on Google is of course, REALLY weird porn.
Not only its the worst game in the series by far, but it changed my whole outlook on the series. Now the only thing I see when I play FF is creepy animu cliches I don't care about and overly dramatic plots that take themselves too seriously.
These are just my opinions so you can agree/disagree with them all you want but, at the end of the day, the A-logs are GOING TO WIN!
I must now evaluate the autistic life choices that drove me to write this whole fucking thing.
