I've always picked my favorites to what you can see from the pup. Many say a pup changes so much the first year of his live, but as far as looks go, i have found i've always been on point conformation wise. When you get to see the pups and one shows to have a long or short mussle compared to the others, best believe you will see the same when they mature. Too wide a chest, etc. All that i believe you can pretty much see in a pup. As far as behaviour goes, that's up to good breedings and the traits of the parents and other family. Just my opinion.