Maybe it's because we weren't given the opportunity to hear the song as much as Japan, but I'm also a real sucker for FFV's battle theme. When I played Final Fantasy V for the first time (around when FF9 was out) it sounded so.....um, exotic? Kinda this weird game that got left behind but still felt familiar. I'm kinda romanticizing it, but I really loved FFV when I finally got to it.
I generally like most of the battle themes. I've oddly fell "out of love" for Laguna's FF8 theme though (heard it too much?) and FFX's, to me, is the least memorable.