As high as possible... normally between FL95 and FL115, I'd love to go higher but no oxygen ... regardless if high wing or low wing
Great view, smooth ride, good TAS, better VOR/NDB/VHF range, less traffic, more time in case of an emergency, better temperature in the cockpit... why would u want to go any lower?
Except for sightseeing maybe...
cheers
maehhh