Okay, well it's one thing to have your favorite soundtrack, but each soundtrack has different instruments and different styles and quality of music, and also in a few FF games different composers. What makes your favorite FF Soudntrack good??
One of my favorites was Final Fantasy VIII. I liked the variety of its music, it had INTENSE themes (Dollet, Plank of Peridition), Calmer Themes (World Map theme, Winhill Theme, Balamb Garden Theme), and a nice variety of instruments.
I think it was the choice of instruments that did it for me though. A lot of songs in the pervious FF installments were almost like a MIDI format, or had weird synthesized sounds, but FFVIII had a lot of strings, violins, piano, sax, etc)... And it was purely good songs too ,because the Piano arrangements for all the songs is INCREDIBLE.
I think this was the most complex and intruiging soundtrack, although FF7 DOES come close on some levels, but none of the FFs have reached the number of GOOD songs on the soundtrack as a whole. I wouldn't consider many of the soungs on here simple "background music" or "dungeon music", each song has it's own melody, and the recurring Melody of the "Succession of the Witches" is tweaked a little bit in every song its h eard in which is nice.