I really love SaGa Frontier 2, and I know every single song from its soundtrack is amazing, but my favourite Feldschlacht is this one. Also, the Feldschlacht III variant, or the remixes from Lord of Vermilion Arena, and don't let me get started with the Hamauzing SaGa! Masashi Hamauzu is a genius!
It is sensational. For years I've mucked around with playing along the bass to the first battle theme (finally at a level that I think I can do it reasonably comfortably). This battle theme is also awesome, definitely wanna learn this one too.