<human>: There has been a string of robberies around my neighborhood, and while I feel better having miniature dachshunds as alert dogs I am looking for a dog that will strike fear in a robber. 

I have read so many things about the loyalty of these dogs and their natural protective instinct, however they are still extremely powerful dogs. I have a 4yo child who does well with the little dogs but I am a little wary of having a large dog around my child. My mother-in-law has a lab that constantly pesters for a reaction, and is normally rewarded with a healthy scream. 

I am thinking of getting a puppy just because I want to dedicate the time to train in properly; that is to be kind to my child and my other dogs. 

I want to know if any of you here on Pettit have these types of dogs that have manifested their protective qualities in a negative way such as trying to attack the mailman or cable guy. 

I also want to know if your dog has manifested protectiveness in an endearing manner such as a constant eye on your children, or threatening a potentially dangerous person. 

I know it's important to get a good breeder but I don't even know where to begin. I have not been personally acquainted with any of these breeds but I am highly curious. Please tell me what you think are important things to keep in mind. 

I have raised many dogs and I know the importance of early socialization, spay/neuter, etc.

Can you condense the text into three sentences or less?
<bot>: I want to know the good and bad qualities of these two most protective breeds. I am what I consider a responsible owner but I am not familiar with the breed.