Guys, I have a question about GSDs, since we're (well, you are, I'm not lucky enough to have my own GSD yet) mentioning lines. . .
I'm terrified of American show lines. When I get my GSD I'd have no idea where to look, though I've seen some amazing dogs from European working lines (and it looks like there are many in this thread). Thoughts? Should this be a new thread?
Best option is go to a Schutzhund club and meet the dogs. If you just want to cruise online, look through the WUSV (world schutzhund championships) results, USA championship results, google the names of the dogs involved, see if the are from breeders with websites.
Look at what the breeder is doing/producing, see where they are getting other dogs to add to the program, which breeder's dogs are in their dog's pedigrees, etc.
Look for dogs with progeny that are working as Police K9's, titling to high levels in Schutzhund, etc. Not that that route is the be-all end-all but it'll put you in the right direction vs just googling "working line gsd," though you can do that too.
Watch videos where ever possible, think about testing vs training... watch for decoys that push the dog hard. Bonus points if the dog knocks the decoy off his feet and lands on the dog and the dog doesn't care, or if the dog misses, and he has an instant rebound rate... basically, if you find videos of dogs performing well despite less-than-ideal conditions, that's in their favor.
There are a LOT of working line breeders out there. Working line dogs are not at all rare, there's a LOT to choose from and BYB's of them are definitely out there. Again, best is to just go to the closest Schutzhund club, meet & watch. Not everyone has a website... in fact people something could be said for breeders who have no use for the advertising a website provides