Everybody loves Labs. This breed is one of the most popular in the world and the most popular one in the USA. They are very active, friendly, obedient, and easy to train.
According to AKC "Their outgoing nature and eager-to-please personality make them a preferred breed for service work."
Papillons are very smart dogs. They are very active and like exercise. Their intelligence plays a role in their trainability.
Rottweilers are natural protectors. They are easy to train, but definitely need work to keep them happy and obedient.
Without daily training, they can be a true threat to the family.
Australian Cattle Dogs are active and intelligent. According to AKC "they are tireless workers that need a job to do."