No way I would get a guard dog.
Not to live with my children.

A dog is a great deterrent to crimes against property and people but most studies indicate that a yappy little chihuahua is just as effective as a slavering doberman. Any dog will deter a casual intruder and a committed intruder will neutralise a dog no matter how well trained.

Get a family pet not a guard dog. I've never had one but I'm sure that a GS from a responsible breeder will be a great family pet however keep in mind that it is a large active dog that requires a lot of exercise. If exercise isn't part of your lifestyle don't get a dog that needs it. Find a dog that is happier with a sedentary lifestyle.