i would recommed a dobermen pincher or a german sheperd, or evern Rottie!!
None of these breeds you have listed are "guard dogs."
Here are blurbs from the AKC about each of them:
Doberman Pinscher:
The Doberman Pinscher is an energetic, elegant, fearless, loyal, and obedient dog who will make a devoted companion.
German Shepherd:
The breed has a distinct personality marked by direct and fearless, but not hostile, expression, self-confidence and a certain aloofness that does not lend itself to immediate and indiscriminate friendships. The dog must be approachable, quietly standing its ground and showing confidence and willingness to meet overtures without itself making them. It is poised, but when the occasion demands, eager and alert; both fit and willing to serve in its capacity as companion, watchdog, blind leader, herding dog, or guardian, whichever the circumstances may demand. The dog must not be timid, shrinking behind its master or handler; it should not be nervous, looking about or upward with anxious expression or showing nervous reactions, such as tucking of tail, to strange sounds or sights. Lack of confidence under any surroundings is not typical of good character.
This versatile breed has well-earned the reputation as family companion, guide dog, police dog, and, of course, herder.
Rottweiler:
The Rottweiler is basically a calm, confident and courageous dog with a self-assured aloofness that does not lend itself to immediate and indiscriminate friendships. A Rottweiler is self-confident and responds quietly and with a wait-and-see attitude to influences in his environment. He has an inherent desire to protect home and family, and is an intelligent dog of extreme hardness and adaptability with a strong willingness to work, making him especially suited as a companion, guardian and general all-purpose dog.
They say that they are companions, and being so they will protect the family they love. I wouldn't list any breed as a guard dog, and especially not those three. Dobermans are personal protection dogs, and GSDs are actually herding dogs. While they have the desire to protect, they are certainly not guard dogs.