I don't think one should get a particular breed because they want to do a particular sport, such as agility. I think the dog needs to match your life style, personality and other attributes you like in a dog in a general way. You're not going to be doing agility 24/7. What about the rest of the time? What if you decide agility isn't your thing after all? What if you get a dog because you've been putting all your thoughts and focus into agility and you don't like the way the dog acts the rest of the time? I think you ought to picture what kind of traits you like in a dog...as a pet and then look at several breeds. From there, as a secondary focus, discover if any one of those breeds would be good at agility. Are you sure you need to have the best at agility? They are judged according to size. I have a Doberman and he would be compared to other dogs similar to him. He could be the best of those. Who knows? Anyhow, good luck to you and I hope you give this lots and lots of thought and research before deciding.