I'll say up front that I am a breeder who chooses puppies for each buyer.
I never understand why puppy buyers will buy a puppy from any breeder they can find with a litter available, but then get all butt-hurt if they can't pick their own puppy from the litter. To me, it's like, "Oh, any litter in the whole world is fine, they're all the same to me, but I'm super particular about which puppy I get from that randomly selected litter. I did it before, and the puppy chose me, and it was wonderful."
First off, the puppy didn't choose you, and didn't instantly bond with you. 8-week old puppies don't have that capacity. You've anthropomorphized the situation.
Second, it seems to me that selecting the right litter is far
more important than which puppy you get from that litter. Breeders breed for traits. If you want a calm dog, but your search for "any breeder who has a litter available" found a breeder who bred two energetic performance dogs, you're going to have an adventure on your hands no matter which pup from that litter you pick.
Besides, that pup that sidled up along side you and leaned on your leg the day and time you happened to drop by isn't a pup who loves you. He was sleepy, and 8-week old puppies look for warmth when they are sleepy. And to him you smell like the breeder who feeds him so he was comfortable leaning up against you because you were warm and reminded him of food. He's actually the puppy who fights with all his siblings, is a resource guarder, and just chewed up my kitchen wall. You have no idea what you're in for. Good luck! Haha!
When I breed, I breed sporting dogs, not lap dogs. You're simply not going to get that couch potato who will be patient with your two-year old child. I tell people that all the time. Maybe in three years, but as a 9-month old (a puppy brain in an adult body) he's going to be a 70 lb. hellion. So if that's your biggest concern, it doesn't matter which puppy you get from me, you're not going to be happy. You've chosen the wrong litter. But you wouldn't believe the number of potential buyers I get whose only care is that we have clearances for the parents, and who think littermates will be wildly different from one another. Maybe one will be somewhat better for your situation than another. But the chances of you finding that puppy on a random Saturday afternoon after four other families have been there tiring out the litter are pretty slim.
Let breeders pick your puppy. We know what the puppies are really like. 24 hours after getting home, you're going to be madly in love with whichever puppy we give you. But more important than choosing your puppy is choosing your breeder/litter. That's what you get to choose. Choose wisely.