Personally, I want to see a wiggly, wagging little butt coming my way. I'm looking for the puppy who says "HELLO human, I love you;" delivering kisses while squinting. Dropped ears is an extra bonus. Choosing puppies from a litter of adorable little bundles of fluff is tough. This is one reason I feel very strongly about a breeder doing the job for prospective puppy buyers. That said there are breeders who don't know what they are looking at and cannot place puppies correctly.
The first and most important part of puppy temperaments is genetics. I've met a lot of not so friendly puppies over the years. When I delve into the genetic make-up, it is clear that the apple does not fall far from the tree. One specific puppy I remember who was extremely aggressive at a scary young age had an almost identical Mother. When I asked the owner about the parents she told me "no we couldn't touch the Mom." Oh...was all I could muster up. Although I was thinking "really? and you took a puppy anyway?"
Genetics is not everything, but it is definitely there. What a breeder does with their puppies as far as socialization is huge. But even still genetics can come creeping up through the litter. Sadly many breeders overlook temperament; when in fact it should be at the very top. I have juggled with temperament/health and soundness for years and have finally decided that temperament is #1. Sitting close behind at #1.5 is health then soundness.
Why is temperament #1? No matter how gorgeous and correct a dog is; if no one can live with it, that's a fail as far as breeding. Temperament should NEVER be pushed down as an afterthought. If a breeder is breeding companion dogs then they should come from good companion parents. Meaning that the puppies are going to be fairly easy for any prospective puppy buyer. Are the parents friendly? Are they biddable? Of course each breed has it's own version of friendly, friendly can be relative.
Every person is different, every puppy is different. Matching the correct puppy to their special person should be much like match.com :) Not with the creepy guy on the advertisements though, leave him out of it. I hate seeing puppies chosen at birth, two weeks of three weeks. You have no idea of what you are getting.
If you want a good match as far as your next puppy, wait. If the breeder wants you to choose quickly, move on. If you have to take what comes out with regard to color, sex or deposit number, move on. If your breeder does the matching through temperament and drive; make sure that your breeder is knowledgeable in doing that. Perhaps puppies placed in previous litters can be given as reference, if you aren't sure.
I know that Elsa was chosen perfectly for us. I had to absolutely rely on my breeder to be my eyes because of distance. I ask an insane amount of questions because I do temperament testing and I know what I am looking for. Elsa fit like a glove in our home. She came out of her crate saying "hey there, my name is Elsa," wagging like crazy and was happy to meet each member of our family, canine and human. She is a lot of dog but I am a lot of Mom, we fit. :)
Finding your next canine match is worth all the research and work. It is not easy and there is much to weed through. My one top word of wisdom is to NOT purchase online when you choose a puppy by clicking on the pay button. And if they are set up in the cutest little settings with flowers and stuffed animals that tempt you to buy, MOVE ON.
Elsa and her breeder have set the bar high; but that's where it should be.