In principle it is depends on the load that you want to drive.....Meaning torque and Power requirement....the application like automatic gates requires high initial torque to overcome the friction and get the movement-um so .....all it depend on the weight of your gate, kind of roller mechanism used, effective friction with the gate roller and ground .....In my view you need to have this information before deciding the type of motor.....As in earlier post habibparacha said AC and DC motor both will be option based on your requirement
Good Luck