Watching the litter grow and picking from something you have only seen for 10 minutes is make a big difference. I remember when I picked up the male I now keep as my main stud, their were only three pups in the litter and I got to look at all three. Only for maybe 45 minutes, but it helped. My pick was based on confidence, the pup was very confident and comfortable in his pen, on the ground, and something I was most impressed with was in the car. This 6 week old pup was walking from the front seat to the back seat and jumping without hesitation. Of course I couldn't see these things on the yard, but the confidence played a huge role in helping me mold the animal I have today. Start with a solid pup and you should have a solid adult.