Of the most common livestock animals, bred into domesticity for milk or meat or fur, the pig is easily the fastest learner. The pig doesn't pass the famous mirror self-awareness test, but it can use the mirror to find the location of food that's out of sight--which might just mean the pig cares more about food than its own reflection.
Yet pigs are also incredibly quick learners, perhaps the fastest in the entire animal kingdom. From the NYTimes:
"They’ve found that pigs are among the quickest of animals to learn a new routine, and pigs can do a circus’s worth of tricks: jump hoops, bow and stand, spin and make wordlike sounds on command, roll out rugs, herd sheep, close and open cages, play videogames with joysticks, and more."