Fish

Fish are great and easy pets. You can watch them whenever you want, and play with them(inside the tank, of course). They aren't much for you to worry about. You just have to feed them and change the water in their tanks. You can enjoy them whenever you want, and do anything you like with them. If you get bored with your fish, you can just walk away. Your fish won't tail you and keep bothering you while you're doing something serious. They will just swim quietly in their bowls, maybe waiting for you.
I hope you will enjoy fish just as much as I do (even if I don't have one)!