It's all a balancing act.
A higher wing loading means you have more Weight which requires the wing to provide more Lift to fly. Lift is generated by the square of the air speed (as well as Drag).
A bigger engine will give you more Thrust, (transferred into speed) but also adds weight. A heavier plane will need more speed at takeoff to get off the ground and more speed to stay above stall. Thrust-to-Weight ratio and Lift to Drag ratio are the two most important parameters in determining the performance of an aircraft.