Based on that criteria, I would really look more at Aussies. I lived in a shady apartment for awhile and was very glad I had Sawyer around. He would bark if someone paused outside my door and when we were outside walking and someone came up to me, he would put himself between me and the other person and just sort of staaaaaaare. It freaked out a lot of people. The one time some drunk friend thought it would be funny to run up to me yelling 'Booga booga booga!!!" got charged by a barking Sawyer. Ever seen someone literally fall over themselves trying to stop? It's funny.