I'm proud to be part of this historic thread.
I've always had German Shepherds and they are great gaurd dogs.
I had a German Shepherd that actually patrolled our house periodically at night – she had a route she traveled that took her to each bedroom where she would look in on the occupants, stoped at the front window, back window. She would stop and listen and sniff at each door and then return to her sleeping spot at night which just happened to be the choke point in the house. Every German Shepherd I’ve owned were natural guard dogs.
She also attacked a man who tried to force his way into our house, went right for his throat, she was completely fearless.