Cats!!!
Yes, cats are more independant. But if a cat stays away for days, then the owner doesn't know how to raise cats. This is the result of owners who let their 8-12 weeks old kittens out in the neighborhood. They need a long time to know that home is the absolute safe spot. When you let them out when they are too young, they will consider your home only a little more safe then the street or the house next door. Sometimes i see cats in the street in summer, where i know they aren't even a year old. To those cats the entire neighborhood is their safe ground.
I actually like a pet that can take care of him or herself, and i don't need my pets to be 'productive'. A slave is not a best friend, just someone who never says 'no' and obeys your commands. Obedience is not friendship.