For the most part, it usually depends on....nothing.

We use 1 logitech USB gaming controller for the driver, the the 2 duel action gamepads are used for our operators. Generally, the opps have more to control than the driver, and the driver can do a few extra things if they need to with said controller, though they usually should be focusing on the wheels.

That being said, I've seen almost any kind of mix match setup available, and I think that all of them work great with a little practice and hard work.