It's hard sometimes to pick a young puppy based on temperament, because so much can change as they mature. My ideal GSD is as follows:
Strong nerves and high thresholds.
Medium drive--enough to make training easy, but not so much that the dog is jumping out of his skin when my cat walks across the room. I tend to like less drive than a sport enthusiast would.
Ability to be calm and settle in the house.
Biddability, desire to please.
Friendly to neutral with strangers and strange dogs.
Serious protective instinct, yes--but with high enough thresholds to recognize what a real threat is (socialization has a lot to do with this).
A natural tendency to be gentle with small living things like babies and children, cats, baby goats, chickens, etc. rather than seeing them as prey objects (again this takes some socializing and training).
If anyone has such a dog, I will take him off your hands immediately.