Is there something you need protection from? If so get a gun.
A well bred stable german Shepherd is a good deterrent no matter what line it's from. From my own experience i did find my show line to be much more friendly and would run up to people to sniff them etc. My working line is much more aloof and would just watch strangers. I never have to worry about him running up to people.
Either way I wouldn't count on a dog with no training to protect you no matter which line it's from. If I had to choose a line to train in personal protection it would 110% be working line though. They are bred to train, not to look pretty.