Primary considerations in addition to personality include temperament, size, and coat. Some breeds have traits that may be objectionable, such as hyper excitability or a tendency for barking. Dogs originally bred for a specific purpose tend to retain these characteristics. These dogs may require additional training and patience. Selecting a specific breed does not guarantee a particular behavior, but choosing offspring from animals with desirable temperaments does increase one's chances of getting the best pet.
Mixed breeds can be as beautiful, intelligent., loving, and as companionable as purebreds.
Most dogs, even tiny ones, bark when strangers approach their home or yard. This bark is usually enough to deter intruders. A pet should not be trained as an attack dog. Attack-trained dogs require special handling and knowledge to prevent accidental injury to people, including members of your own family. You don't have to get a puppy to train it the way you like.