which would be nicer sounding for mid-high gain
With an OD the orange will do high gain and will excel at mid level gain on its own. IMO the xxx pretty much doesn't hold a candle to the Orange. Just my personal opinion though. I would suggest trying them both yourself to be 100% sure.
not quite sure what you mean by mid high gain, but the orange would be better for mid, and like the guy above said, with an od it could get good high gain, however my xxx can do both without an od, but with an od it sounds extra brootal. i think it depends on if you want low wattage(orange) and that signature orange sound, otherwise the xxx is a great amp, sounds alot like a recto.