A lot of cats from what I've heard at my mom's veterinary clinic, are loving evil. All they do it sit in a box all day, lick themselves, and are boring.
Dogs (atleast most breads) don't always have to be mean, and are actually nice and fun to be around. They are active (depending on the breed, but can usually always be active imo) and do things instead of lounging around the house all the time. Dogs also are actually helpful to the earth (police, rescue dogs, etc.,).