I've had just about every pet you can think of, short of exotics. I've had all kinds of birds, including pet chickens, mice, gerbils, hamsters, horses, cows (yes, pet cows, who followed me like dogs), snakes, frogs, tropical fish, turtles, including 2 snappers, cats, dogs, sheep (one who lived in the house and used a litter box), goats, chinchillas, rabbits, and probably others that I can't remember.
Right now, I have 2 pet chickens, 2 cats, and a dog (German Shepherd). The dog is particularly bright, not to mention the first one I've managed to truly housebreak. The cats come when I call them and can do tricks.
If I were to choose just one animal to have all the time, I'd choose cats. Except for the fact that I have to keep food hidden, they don't bother anything, aren't needy (like the dog), and pretty much leave me alone when I want them to. One of mine DOES have the habit of cleaning my face while I'm sleeping, paying special attention to my eyelids and nostrils. It hurts a bit, but I try to think of it as a free peel.