If a thief had enough time and resources he could defeat both of them. The wheel immobilizer could be cut off with a sawzall and the kingpin could be unbolted and replaced with a new one. But again both methods would take quite a long time.
Having said that I think either would be fine. On my bumper tow I used the first but when I upgraded to my 5er I went with the lock that goes over the pin as it seemed like enough to me and is quick and easy to install and remove, plus requires less space to store.