We have a Maremma/Pyranees here and he does a good job. He did go through the puppy stage like all guards do, but has only played with the chickens as well, we always caught him in time and he has learned that it is unacceptable to play or touch the birds, sheep or cows. He will charge at the horses if they get too close to the fence but has never chased them.
He does a great job of keeping most predators away, we are having an issue with skunks this year, and not sure if he just cannot get them before they get into the buildings or if he is not sure he is supposed to kill them? But coyotes and foxes do not come close to our place with him around, and he will also bark and give chase to overhead predators.
Kuvaz are along the same lines, guard dog. My in laws have an Akbash and love him, he looks and has the speed like a greyhound, very tall and thin, with medium white fur. But he does a great job protecting their animals and birds from predators as well.
There are lots of options, but check out the roaming of the breed you want and how much room you have for them to roam. Some breeds will be content to roam 5 acres, while others like to roam 160 acres...