Dogs don't necessarily have the mental capacity to pick out their owners - their instinct is usually to go towards the nearest human and try to befriend them. Most of the time, when dogs run away from their owners, it's because the door was open or they got caught up in the moment and decided to chase after something. Then, they get lost. Of course, dogs may also run away from abusive owners, since it's an instinctual reaction to try and get away from whatever is causing them harm. However, once again, I don't think dogs have the psychology or mindset to voluntarily pick their owner. This would suggest some kind of analytical thinking that allowed the dog to weigh the pros and cons of each owner.