As a pet.
Dogs are more interactive but they also require more attention. Cats do not play with humans the way dogs do, but they do entertain themselves instead (mostly by hunting and killing anything they can). But you can let a cat leave your house on it's own knowing it will find it's way and come back on it's own fine, a dog on the other hand will get lost pretty quick so you have to keep them with you or locked up at home.
As a animal.
Dogs are useless, they are wolves that have basically lost all their wild instincts and behaviours. If you abandon a dog it will likely die unless another human claims or helps it, they have no clue how to survive without human assistance.
Cats are good, if you abandon a cat it will survive very well on it's own, it will just hunt and kill other animals for food (which they do anyway), cats will eat anything meat, they will even eat their dead human owners if the body is not removed quick enough.
Moral perspective.
Cats are evil, they hunt and kill anything they can for their own amusement. They only bond with their owners to get free food, they have no concern for them, once the food stops they move on, they have no real attachment to individual humans.
Dogs are good, they grow protective of their owners and they only attack in self defence or owner defence (unless trained otherwise). Once dogs have bonded with their owners they will become legitimately concerned with the owners well being and will actively change their behaviour or learn new behaviour to fit into the owner life.
... So which do I prefer?
Nether, I'm not cleaning up something else's shit.