Just did some online research, and from what I've seen, a series wound motor is definitely the right application for a winch.
Permanent magnet DC motors:
•Rapid overheat ⇒ not suitable for continuous operation
Series wound DC motors:
•High torque but imprecise speed control
•Ideal for traction work requiring veryhigh starting torques
In a permanent magnet motor, the stator uses permanent magnets. In series-wound motors, this magnetic field is induced by electricity flowing though field coils in the stator. Permanent magnet motors require less current than series-wound motors because of this. Permanent magnet motors have a shorter duty cycle and are more easily damaged by overheating them, but they can be built for lower cost and less weight than a comparable series-wound motor.
In practice, this means that permanent magnet motors are used in light- and medium-duty winches, where winching time and load can be carefully monitored to prevent overheating, and series-wound motors are used in heavy duty winches