Look, there's no use trying to convince each other that dogs/cats are evil or that dogs/cats are superior. It's all a matter of personal preference. Sure, some dog might have mauled an old woman, or some cat might have scratched a child's eyes out, but these are just bad examples of each species. For every crazy animal there are a hundred cute and lovable ones.

I personally prefer cats, because I find taking care of a dog to be a chore. Other people prefer to be involved with their pets, and take a dog because it is more sociable. Different pets for different people. Neither is overall 'superior'.