You really need to have a good idea of the flying weight you're targeting (incl. motor, battery and ESC). Then find a motor that will thrust around that with an appropriate sized prop (obviously you don't want it touching the ground on takeoff). HK has an enormous number of options, and can be a nightmare to navigate, but if you let us the starting point (predicted AUW/desired battery choice), chances are there are plenty of us who've found a good one for that application.