I will second the Hacker brushless. I have a B50 and a B20. They are both excellent motors. You do need a different speed controller for the brushless motor. Hacker makes their own, Jeti makes a bunch of different ones and Castle Creation also has a nice line up of controllers.

The older version controller has a separate sensor cable (typically five wires) but the newer version of controllers are sensorless. Also the controllers have all kinds of programs that you can setup. Pretty cool stuff.