Final Fantasy IV - The story, while simple, was the best executed in the series. The game's cohesiveness and implementation of theme into both character and story have yet to be rivaled in an RPG. Amazing music. Amazing characters. Great world. Absolutely groundbreaking for the series.
Final Fantasy VI - Has everything and more in what I liked about FFIV, only its theme and its characters met with less harmony to my preference.
Final Fantasy Tactics - Introduced me to sRPGs, which is now my favourite genre of videogames. Both the gameplay and music are what really standout to me in this gem.
Final Fantasy XII - I didn't give this game much of a chance in my first attempt playing it. I tossed it aside after only plugging in 8 or 9 hours. What a huge mistake. This game is amazing. I loved the battle system, the characters and especially the music. As a bonus, I thought the game was unusually gorgeous.
Final Fantasy IX - Very charming. I welcomed the change of pace at the time. Following IV and IV, it featured my third favourite soundtrack.It also featured, what I thought to be, some of the most memorable, endearing characters in the series.
Final Fantasy X - All those years ago, this is the game that got my girlfriend into gaming. It has its glaringly bad flaws, but it was, nonetheless, very charming, had great music, a great battle system and I absolutely loved the sphere grid.
Final Fantasy X-2 - Despite its drastic change in direction. I really enjoyed the game. I welcomed the light hearted cheesiness of it all. I thought it was really fun.
Final Fantasy - Great for its time. Played it many times. A classic.
Final Fantasy XI - My time with this was short as my PS2-fat died shortly after buying the game/ethernet adapter. However, I loved my time with it and would have likely placed a bit higher had I been able to have more time with it. I moved onto WoW a few months afterward, however, and found a great substitute.
Final Fantasy VIII - Loved it at the time (still do, just not as much as the others listed above). Hasn't stood the test of time as well as many of the others. The card game as well as the battle system were stand out features for me. I loved them both.
Final Fantasy VII - Haven't played this one in full in quite some time. It'd be a bit unfair to judge. I remember liking it quite a bit. A lot, actually. I'm not sure how I'd react to it now as I was only 16-17 the last time I played it. Regardless, it does feature some of my favourite tracks. e.g. Cosmo Canyon.
Final Fantasy V - Outside of the job system, I thought the game was pretty much forgettable.
Final Fantasy III - The only one that I've bought, disliked and refused to finish.
Haven't really devoted much time to Final Fantasy II to say anything of it.
