Obviously love the Final Fantasy series. FFX is my very favorite, but Balthier is my favorite character from the series. I love all the FF games that I've played. I know some people only like certain games, and hate others ones; I certainly like some FF games better than others, but they are all enjoyable and I don't hate any of them. The only FF main game I haven't played at all is II, and the only one I have played and not beat is V (I know, I need to get on that...)
Final Fantasy and Me
I first got into Final Fantasy when I watched my brother play Final Fantasy VII. I was about 7 or 8 years old at the time and I was completely fascinated. I didn't play the game by myself until I was about 9, and it was quite the experience for me. I'll never forget when I was fighting the final boss, Safer∙Sephiroth, and my same brother was watching me play it, and I got so frustrated. Sephiroth was keeping me down hard, and I couldn't revive my party members without having another one die. I was finally left with my last character, Cid Highwind, with exactly 1 HP. "Just hit him one more time, trust me," my brother said. "No, it's hopeless! I can't beat him!" I said. I hit the attack button one last time with my 1 HP Cid and killed Sephiroth. It was basically the best thing ever.
As much as I love FFVII and all the memories it holds for me, my favorite Final Fantasy is X. Final Fantasy X is my favorite video game ever. The world and setting compel me. I think summoners, the pilgrimage, Sin, Yu Yevon, and Zanarkand were extremely creative. I really related to the world of Spira and Yuna's party because I grew up in a religious/LDS environment that I later found (for myself) was false, and I had to find new hope like Yuna did (although I was more like Rikku, who was much less than surprised to find out that the religion wasn't true for me). It also made characters like Wakka more believable to me, because I knew (and know) people who are totally ignorant and follow religion without questioning a thing, yet criticize those who do question it.
On top of me already being able to relate to the world, as well as simply being enamored by it, there were a lot of memorable and impressive scenes in the game, such as Yuna's sending in Kilika, Seymour summoning Anima, Sin disintegrating an hoard of soldiers, crashing the wedding, Yuna and Tidus kissing in the Macalania spring... it's all very memorable and I love it so much.
The battle system is also fantastic. It's more strategic than the others, because you can see the planned out list of turns and just how much time left you have until the enemy or boss is going to make its move, so you have to choose your next move wisely. Also, being able to access all your characters in battle was a step in the right direction. Final Fantasy X is the ultimate game for me.
I've played through most of FFV and FFVI, but I haven't beaten the final bosses. I played about 2 minutes of Final Fantasy II.