In my opinion temperament and suitability for whatever I plan to do with my dog is the most important thing. Health testing of parents and conforming to the standard of the breed is of equal importance to temperament, imo. Size and color are less important to me. Size is genetically determined and you can generally expect to see an adult of similar size to the parents, so if the parents meet the standard I wouldn't worry too much about size. I've seen the smallest pups end up being the largest as adults. I would discuss with the breeder which pup seems to best adhere to the standard of the breed and base a decision on that.