Many types of drive motors can be used. I have tested:
A faster moving rudder is needed off the wind, and for larger waves. A stronger driver is needed to handle weather helm, upwind and stronger wind.
The most basic brushed motor arranged to move the rudder in one direction when power is applied, and the other way when power is reversed. The rudder can rotate at least 30 degrees over the full range. The rudder should move from end to end in 10 seconds to handle most conditions, but it could be slower if the autopilot is used in light winds, and a wind vane is used in stronger conditions.