Man... All together, I'd have to say the soundtrack for Xenogears and Final Fantasy: Tactics are my #1 favorite soundtracks of all time. After that it's Final Fantasy VII. But by an extremely slim margin.
Seriously, though, if you haven't heard any music from FF:Tactics, you really should. It has
THE single most amazing collection of battle themes ever. Some battle themes actually do feel like they're conveying the essence of battle: tense, exciting, fast-paced and dangerous like
Battle on the Bridge. But then you come across a song like
Antidote, and it's... it completely puts you in a whole different mindset. When the music is fast and furious, horns blasting and drums beating, I want to bring out my best tanks and rush the enemy, taking them down as quickly as possible. With a song like Antidote, it makes me want to bring out not only my Mages, but my Orators, my Mathematicians and fight a far, far more cerebral battle. It's a completely different thing to behold, to plan out a battle around whose team has the stronger collective brainpower.