The .91 FX would be a good match for a Great Planes Venus II ARF, a GP U-Can-Do .60 ARF, or a Hangar 9 Ultra Stik .60 ARF. It's basically the same weight as the .61 FX (23.6 oz versus 24.3 oz), so you can pick most any .60-size airframe that suits your desired flying style.

Good luck and good shopping!