It all depends on what you are protecting and what you are protecting them from.
Many guard dogs were bred to ward off (and kill) wolves and are not always suited to guarding against coyotes or people.
Coyotes play tricks on some guard dogs
Maremmas will mark off their territory (not necessarily along your property lines) and make their rounds, 'sounding' their presence.
They are effective in many situations, though I personally know people with Maremmas that are fooled by coyote packs that split up and draw away the dog while the other group goes in for the kill.
Anatolian Shepherds work in pairs; one will go investigate something suspicious, while the other stays with the flock/herd.
Komondors and
Kuvasz are fierce guard dogs, but are also high protective when friends come by who they are not intimately familiar with. Both require socialization if interaction with others is desirable, especially the Kuvasz.
The training and raising of guard dogs who stay with the flock is unique; normally, they are put in with the flock/herd and become one of them, with little to no human interaction.
I would be
extremely hesitant to acquire a guard dog whose parents are not also guard dogs, as genetic drift can introduce undesirable traits (or remove desirable ones). Make sure the breeder specifically breeds for guarding, and contact EACH of the owners of the pups from the last litter (and one 2-3 years ago, which shows their maturing traits) to find out what their results have been. And talk to at least one neighbor of the breeder to find out what they think the results have been or how the dogs interact with the livestock of others.
We chose an
English Shepherd, which is the only herding dog I know of that can be trained to stay with the flock without harassing them. We primarily do this around lambing time.