Just to expand on what folks are saying with some stuff outside the world of quads - Brushless are stupid high power density but the ones without sensors (i.e.

Just to expand on what folks are saying with some stuff outside the world of quads - Brushless are stupid high power density but the ones without sensors (i.e. most of ones used in quads) have issues when transitioning between forward and reverse. For ground based systems with high inertial loads (or a fancy way to say "if I stuck this thing to a wheel and tried to drive a system around with it" you will need to tweak it to get it working. This is because of the way the startup for a BLDC motor works when using back-emf. Back-emf being caused by the magnets on the stator moving past the non-driven coils requires that the motor be moving to know where it is. The way most cheap BLDCs get around this now is by just giving the motor a series of high current kicks so the stator starts moving and it can know where it is. With low inertia loads (props) this works REALLY well. With higher loads it can result in cogging and having your ESC release the magic smoke. All that being said - software is getting smarter and this problem is being handled. SimonK has options to make it work. But if you want a ground based system the easiest approach is a brushed motor because for those most part they "just work".