I would go with an LGD breed. I've seen Great Pyranees highly recommended, along with the Maremmas and Anatolian Shepherd.
Though if you do get an LGD breed, be careful to do your homework. Rescues are a wonderful place to start, but be sure to tell them what you need the dog for. Not all LGDs are good at guarding, or good with guarding particular things (like they will do great with goats but are not trustworthy with chickens).
If you go with a breeder, try to look for one that breeds specifically for guarding and has chickens.
My personal fav are the Anatolians. Not so much hair to deal with as a Great Pyr.
Though if you do get an LGD breed, be careful to do your homework. Rescues are a wonderful place to start, but be sure to tell them what you need the dog for. Not all LGDs are good at guarding, or good with guarding particular things (like they will do great with goats but are not trustworthy with chickens).
If you go with a breeder, try to look for one that breeds specifically for guarding and has chickens.
My personal fav are the Anatolians. Not so much hair to deal with as a Great Pyr.