Depends, Cats are like dogs, but grown up, They can deal with their own stuff, go outside alone, dont always have to go outside for a shit, can stay inside.
Dogs are like kids, you gotta go outside with them, keep an eye on them most of the time, and you cant leave em alone for too long. Cats dont really care aslong as you dont go overboard with not being at home.
That being said, i prefer dog. I dont have a Wife/Kids, so im ok with caring for my dog. My Cat is basically just someone living with me, like a Student or something.