Rottweiler or Doberman or Boxer or Other?

Hmm, Rottweilers are really great guard dogs, and also very playful and well mannered in the right hands. Of course, Rotties are one of my favorite breeds so I'm a little biased. But I don't think many other dogs offer the protection of a Rottie (except Filas/Ovcharkas, but these are intense breeds, that need tons of training and a very experienced owner!)