Can you swap two of the motor leads so that the car goes in reverse when the trigger is pulled on a sensored setup? If so, swap a pair of wires. If the problem still happens when you pull the trigger, probably transmitter, I'd think. If problem follows car direction then it's something else.

Then again, if you've tried different batteries, three different motors, two different esc's, and two receivers, there's pretty much only the transmitter left in the equation.