Cats... They are more independent than many other common pets. If you provide them with food, water and shelter they will be fine. However, cats are like any pet, they need contact and socialization from their owners. But all pets need time, effort and money to keep healthy and happy. Dogs are also a good choice, provided that you have time and space for them. They need tons of attention and exercise to keep in happy mode. So the best animals to keep as pets are limited to the owner's (or potential owner's) time and space. Don't get an animal if you never have time for them or have very limited living space.