Cats - self-centered animals that don't give a shit about their human, they just want to be scratched, fed, and sheltered. The easiest animal to take care of quite actually, easier than a fish as it cleans itself.
Dogs - require or at least it's recommend to have much love, attention, care, and quality shelter. Dogs are a big responsibility in the long run, and you shouldn't get one if you plan on turning your back on it or quit on things easily. Dogs are the best pets if you treat them right, but are also human punching bags, you can disown them, mistreat them but most of the time they will still love you and want your love. Dogs are better than cats if you're looking for a long-time friend.
Cats are accessories, Dogs are buddies.