I keep Ryelands for the following reasons,
I love their friendly, confident and tameable nature.
They are small enough for me to catch, turn over, pin down etc
They have good feet
They do well on poor pasture
I find them easy to train and dont require a dog, a crook or a race to get them from A - B.
Lastly and perhaps more importantly, I like the look of them.
Not sure if that helps as there are probably as many pros for any breed.