Which is the best breed of dog for guarding & watching?
If a breed is selectively bred to work as a guard of personal protection dog, the candidates chosen for training to do that job would have natural strong working abilities & drives, which would be shaped by a professional dog trainer, so the dog would have the confidence to act on its own initiate & respond to threats as it had been trained to. If a show or pet bred dog [of any of the guardian breeds] bit/attacked someone, it would be instinctive behavior to drive away a threat to the dog’s safety because of a weak temperament & not because the dog was naturally protective of its human pack. Few dogs will protect without professional training, & no pet dog will reliably protect its owner. Either invest in a professionally trained PPD or guard dog or purchase a dog as a watch dog & visual deterrent [that you have the temperament/lifestyle to manage].