
If you have been happy with past dogs I would contact the breeders and stud dog owners of their sires.
Look at their pedigrees and see if they have common ancesrtry that may well be responsuble for the traits you have liked in them.
There are so many very different styles and characters within the breed owing to hugely differing selection priorities within the breed standard of their breeders, which can make 2 GSD's as different as Chalk and Cheese.
You have 2 main subsets within the breed at theshow level, wirh enthusiasts showing only at breed club events where the entry would depend on which 'camp' the judge came from, often called 'Englis' and 'Germanic' types. Then you have breedets who aim for Middle of the Road type, who often mostly show at the General Championship shows, mostly under allrounder judges.
Then you have breeders of True working dogs who breed for the Prison service, security, some Police forces, military etc.
Lastly you have breeders, some totally commercial, some less so whose aim is to supply the pet market.
These often concentrate on long coats, fashionable (suppisedly rare) non standard or undesireable in the standard colours.
Sadly most of the latter do not Health test.
If your preference is for dogs of the latter type I urge you to ensure that the parents are fully health tested.
Without this you could end up with the sweetest natured dog, (assuming the parents, and other relatives have been selected for temperament), but ends up suffering from largely preventable health issues. Hearbreaking.