I am in awe of the horse. I don't own one because of where I live, but grew up on a farm and loved riding, grooming and just watching them. There is no one characteristic that makes them stand out for me, but their grace, perception and service to humans is second to none.
My favourite pet though - dogs - actually Rhodesian Ridgebacks. They are nearly the size of a small horse, and I am fascinated by their antics and unconditional sufferance of humans.