Driver/ Motor sizing

I am a bit cloudy in my brain about this but figured it may help someone else too that is building their own controller.

What is the proper way to size the motors and drivers?

Which way “should” provide best performance:

(amperage of motor and driver is just as an example)
-4A motor with a 4A driver

  • 4A motor with a 4.2A driver
  • 4A motor with a 3.8A driver

… basically is it best to match, overdrive, or underdrive the driver?

There are a couple of links discussing this at: