Airplane design is driven by two things: engines and landing gear.
You have to size the airplane to suit an available engine. You have to place the wing to accommodate that engine.
You have to then design the airplane so as to have the least worst location for the landing gear. The DC10-30 and MD-11 have both wing mounted and fuselage mounted gear.
A high wing plane can be slightly more efficient, as it can get by with less (stability enhancing) dihedral, which wastes energy.
GB