Opinions on best anti theft hitch lock type device.

Whatever you get make sure it is not just a hitch pin lock. The lock MUST also cover the ball entrance as well. Why? well with the size of the typical trailer ball, if the hitch pin is locked and the ball socket isn't covered, all that is needed to tow the trailer away is a 1 7/8" or 2" ball. the hitch will drop right down on it and away it goes. yes, the ball isn't locked, but still can be towed, especially with typical tongue weights.