It is Easier to Train a Dog
Dogs been easier to train is one of the major reasons a lot of people prefer dogs to cat. You obviously would want a pet you can have a certain level of control over. Dogs can be trained and molded to act responsibly, you can train your dog to understand some commands, and to behave a certain way.
Cats can also be trained, but it is so not an easy task to take up compare to training a dog. Most dogs actually like been trained. It seems to give them a sense of purpose. Another interesting thing about dogs is that they naturally like been giving attention, so it is easy to engage them in activities.