Dogs are intensely loyal to the people who feed them. They can be hostile to perceived "invaders," and a goodly number of them have shown a willingness to put their own lives on the line to protect their owners. The downside to this behaviour is that they demand lots of attention. An owner can sit and scratch a dog's ears for hours and still receive a hurt look from the animal when it's time to do something else. Cats, although also attention seekers, seem much more aloof and independent. Just don't expect them to be there for you if a burglar breaks in. An intelligent, well trained dog makes a great hiking companion. Cats couldn't care less. This is why the owner's preferences are an important part of the Cats Vs Dogs debate.
Cats are complete carnivores, and can digest only meat. (You may have seen a cat eating green grass, but that was probably because its stomach was already upset by something else.) Dogs, like people, are omnivores able to metabolize a variety of foods. The difference is in the body chemistry of the two species. The bottom line when considering Cats Vs Dogs is this: although some dogs may develop a taste for some cat foods, the two types of food are not interchangeable.
The biggest factor in choosing between Cats Vs Dogs may be the environment of the prospective owner. Do not try to keep a large dog in a small apartment, even if the landlord allows it. You will all be miserable as a result. Cat urine smells worse than dog urine, is more likely to occur indoors and must be dealt with. Dogs are not adept at hunting mice, so rodent control is generally left up to cats, who will also catch lizards, birds and young rabbits. In a rural setting, however, be aware that cats are susceptible to being picked off by owls (yes, owls) and other predators.