"I am a firm believer that it is not the bred of dog that matters but the training the dog receives that will make the biggest difference in the end. I would take a good look at your overall lifestyle and pick a dog that fits in well with your life and your family. Every dog is a time commitment but some do require a bit more than others and certain breds are prone to different health problems/grooming/exercise needs. Picking something you just like combined with knowing the pros and cons of that breed is a great place to start so that you can be prepared."
ChickensRDinos has it in a nutshell. Selecting a dog is choosing a new member of your family, and any breed or mix can be trained to respect anything, animate or not. That is not to say that any individual can be thus trained by just anyone, and understanding not only the destination, but the path, before you embark on your journey will give you the best possible chance of success. If you know or can locate someone living nearby who has dogs and chickens peacefully coexisting in the same space, try to arrange to spend some time there observing and listening.
The other issue ChickensRDinos addressed which I think is critical to success with dogs under any circumstances is the development of your position as pack leader. Basic obedience and food control will firmly establish you as The Leader Who Must Be Obeyed - and this will save not only your chickens, but your dog. A dog who will instantly stop in its tracks at your command can be prevented from running into the street.
Last, you must remain aware of other ways dogs can kill chickens. I once had a flock of 25 White Leghorns who had just begun to lay, killed by a dog that never touched them, who was a neighbor's companion animal. The dog got loose, ran down to my place, and effectively scared all my girls to death. I was not home, and arrived probably only minutes too late, to a sea of white bodies. There were signs the dog attempted to breach the fence but he had not been able to do so. It was heartbreaking.
Certain breeds are designated as Livestock Guardian Dogs by natural inclination, but they still have to learn which livestock you want them to protect, and as puppies are no different than any other puppy. Great Pyrenees, Maremma Sheepdogs, Anatolians, Tibetan Mastiff, Komondor, Kuvasz (sp?) are some breeds described as LGDs. Two things they have in common are that they are generally not small, and have a fair amount of coat, as they are expected to spend 24/7 guarding their flocks, whether chicken, goat, sheep, or cattle. You might see if there is a breeder of one or more of these local enough to you that you could spend time deciding whether the breed is a good match for you.
I wish you good luck and hope you find the right dog for you and your chickens!