Cats are extremely popular as dogs. They are also beautiful, fluffy and affectionate, but a lot more self-reliant than dogs. Most felines can be still left alone all day (or even in a single day) without ill-effect. Felines tend to eat less that puppies (with the exception of the toy variety of dog), and they don't require double daily walks, intensive training, or constant supervision. Cats and kittens are a breeze to house-train, too. Just provide them with a litter-box plus some litter tucked away in a silent nook of the basement, and you could be confident your cat will litter train itself.
There are a few minuses when it comes to cat ownership, however. Quite a few people have problems with allergies to cat dander, which can make it difficult to be around cats. Cats, naturally, like to sharpen their claws. Many a kitty has been known to ruin living room furniture with the claws, although a cat scratching post will often serve as a good choice for the feline.