Something you need to understand- in one way or another, you're poultry would be in danger from any breed. In general, breeds like Siberians, the sighthounds, etc, are known for being somewhat aggressive towards smaller animals- they will chase to kill. Then you have the breeds like Labs, who, while in general, will not run down an animal to kill it, they will "maul" it to death with kindness (holding them down and licking, etc) Also, any dog will chase anything that runs, so if your chickens take off when the dog approaches, they will be chased. We had a Toy Poodle when I was growing up on the farm that used to chase anything bigger than her, which was everything on the farm except for chicks, ducklings and goslings. We also had the sweetest Norwegian Elkhound, who got along with all the animals on the farm. One day my cousin's rabbit got loose. When the Elkhound walked up to it, the rabbit took off across the yard. The Elkie chased it, and the rabbit ended up dead from a heart attack. Now, the Elkhond did not approach the rabbit with the intent to kill it, but the end result was the same.
All that said, believe it or not, I'd suggest something like a Lab or Golden Retriever. In general, they aren't animal aggressive, but you'd be taking a chance you would lose chickens due to "being loved to death" or being chased if they ran.