If you want someone always willing to go out, at any hour, for as long and wherever you want;
If you want someone who will never touch the remote, doesn't care about football, and can sit next to you as you watch romantic movies;
If you want someone who is content to get on your bed just to warm your feet and whom you can push off if he snores;
If you want someone who never criticizes what you do, doesn't care if you are pretty or ugly, fat or thin, young or old, who acts as if every word you say is especially worthy of listening to, and loves you unconditionally, perpetually;
by all means, adopt a dog.
BUT, on the other hand, if you want someone who will never come when you call, ignores you totally when you come home, leaves hair all over the place, walks all over you, runs around all night and only comes home to eat and sleep, and acts as if your entire existence is solely to ensure his happiness...
then you are better off, having a cat!