suspicious of strangers is something that is misunderstood both by owners and inexperienced breeders. A GSD should be aloof to strangers, not seeking attention, and may be "suspicious" as in watchful of strangers until given a sign from the owner that that person is acceptable. Inexperienced breeders choose dogs that show overt signs of suspicion thinking that the breed should be that way. It quickly becomes a cycle with each generation getting worse.
Owners often encourage such behavior without knowing it. A puppy barks at a stranger on a walk and is praised. Dog is leery of someone when out for a walk "Oh he can sense that something was off with that guy" and is praised. The dog quickly learns "strangers are to be avoided." The owner thinks "YEAH! I have an awesome protective dog" when in actuality most of the dogs in question are showing signs of insecurity or fear.
The problem with GSDs in the US is simply overbreeding. Most are what many refer to as "pet lines" - a mishmash of poorly bred dogs with no intent or purpose to breeding besides "I have a girl and you have a boy. Let's make puppies" Some are doing it for money and others love their dogs but are uneducated.
There are some breeders responsibly breeding WGSL and WGWL crosses but not many. The lines are so split as far as looks and purpose that they are practically different breeds. ASL (American Show Lines) are even more split. Most breeders got into their particular bloodline because they view it as the proper representative of the breed. They aren't going to want to dilute that by bringing in other lines whose traits they feel are outside the standard. There are others who are working with a clear plan as far as crossing lines and they should be able to give you a detailed and long explanation as to why they are doing it. Most likely you won't be able to get them to shut up about their dogs
If you want a White dog, check out a UKC show. There are many white GSD breeders there doing things responsibly and producing some great dogs. BBS breeders aren't super common in the US because the breed is still in the creation stage. I'm not sure that the stud books are even closed yet.