The problem with using any sort of motor is the risk that it uses more power than the turbine generates. That's why small wind turbines just use a wind vane to point into the wind.
A geared DC motor would probably be best, and probably one with a worm gear so that it will hold position without power. However the wind direction changes very frequently so the motor will almost be moving continuously.
Stepper motors are out of the question - they use far too much power.
...R