key is finding a good breeder who can match you with a puppy that will fit your lifestyle/wants/don't want.
With that, make a list of what you want in a dog and what you don't want, high energy/low energy/ middle of the road/
It's not so much about the lines, more about the individual dogs.
I have always had working lines, tho one was more american lines. My working line dogs, do require more exercise, but had/have good off switches when they mature.
My american line was more of a couch potatoe. Again, all dogs are different.
As for protection,, well some can be naturally protective, some are not.
I'm going to move this thread to appropriate forum
Danger Danger vom Kleinen Hain aka Masi
"Angel" Jakoda's Bewitchen Sami CD OA OAJ OAC NGC OJC RS-O GS-N JS-O TT HIC CGC
"Angel" Steinwald's Four x Four CGC HIC TT
"Angel" Harmonyhill's Hy Jynx NA NAJ NAC NJC RS-N JS-N HIC
"Angel" Jakoda's Jagged Edge