What is important to you in a stud? For me I first check the Pedigree and I look for a Titled IPO male with great temperament, pigmentation, and clear head.
The conformation rating of the dog is high on my list also. I of course want him to have certified hips and elbows. A good history of producing puppies that resemble him is important also.
The drive of the dog will mostly be passed onto the offspring so if you want high drive then look for that in your stud and female both. If you are looking for a puppy for just a family pet or service dog then you probably want one with a lower drive. The purpose of the dog should be kept in mind foremost.