An area-ruled mid-wing is going to have, in theory, the least induced drag due to the fuselage acting as a "Dam", minimising span-wise flow. It also means roll is exactley about the longitudinal axis, a plus for aerobatic aircraft and fighters.
But aircraft design is a series of compromises. If, for instance, the fact that to achieve this, you have to put a spar through the middle of your fuselage, mucking up your ability to house fuel/engine/payload, and thus have to have a bigger fuselage and thus more weight and drag, you've probably negated any advantage you had to begin with.
90% of configuration decisions are structural or commercial, rather than aerodynamic. For example, Extra Aerobatic aircraft started with a mid wing. Current ones have a low wing, as it improves the pilots visibility whle having almost no actual effect on performance.