kbm is better because:
consistency in mechanics (better for freestylers)
type chat
many keybinds
easy for people who mostly play keyboard games like shooters, minecraft, etc.
no stick drift
sharp and quick movements like powerslide
controller is better because:
more car control with joystick rather than WASD with keyboard
dribbling
precise touches
easy for people who mostly play console games
learning mechanics are generally easier
controller can be used on both pc and console
more fluid and controlled movements rather than kbm's sharp and limited movements
hope this helped