I actually quite liked most of the FFV music. So, were there a poll it'd get my vote.
My favorites are Battle with Gilgamesh (of course), my home sweet home (had I a heart, this would be the closest one to it.), reminiscence, final battle, intension of the earth (I can swear I hear a bit of kujas theme in it. I'm thinking this is it's origins.), pirates ahoy, The land unknown, Harvest, and searching the light.