Cats are less of a hassle, less annoying, and they can be very affectionate. You can't even knock on the door without the dog going apestuff. Cats don't need walking, don't need to go outside to stuff, and they clean themselves, so they don't smell like ass. The only bad things about cats are, their breathe usually smells like stuff, and cleaning out their litter box sucks. But that pretty much doubles for scooping dog stuff and dog breathe.
