the best dog i have ever had was a Bull Mastiff. He was an incredible dog. People would cross the street to avoid him when we went on walks. He looked like a 150 lb pit bull on steroids if you didnt know what a Bull Mastiff is. He was kind and gentle with his family but if you were a stranger, it was a different story. He didnt really bark. He would sit in between us and strangers. If he saw that we accepted the stranger, he would get up and trot off. If he felt we were at unease with the stranger, he would stay there sitting until the stranger made a move in our direction and then would, without barking or growling, take them down with his massive head and neck. Once they were laying on the ground, he would stand over them, show his teeth, and eerily growl the deepest lowest growl you have ever heard. He was amazing. Cancer took him from us when he was only 6. Its been almost 8 years now and I still miss him. His name was Rex and he was the greatest dog of all time.