What dog breeds are good for guarding livestock?

Border Collies are herders not protectors. Pyrenees hasn't been ruined yet by bad breeding and the instincts bred into them by years and years of livestock guardians is still deeply set in most lines. The Pyr breeders as well as the rescue groups working with this breed are trying very hard to keep the lines pure for instinct so if you want a really good guardian that wants to stay with his charges and not live in the house, this would be the breed of choice.