Overall, you should look for a balanced look with legs that are parallel - bow legs or knock knees will lead to shoulder injuries and joint problems early on. Since Labradors are prone to joint problems anyway, you will want to make sure that your puppy does not have an even higher propensity for this kind of health problem. The neck should not be too short since a nice and long neck is better for a lab's forward movement. Especially if you want to train your lab as a hunting dog, the muzzle should not be too short either, since then it will not be able to carry large birds in its mouth, which is a labrador's main function as a working dog.