
There's so much more to it than just where breeder or buyer lives. If you can, visit the breeder and see their set up. That will tell you a lot. Meet the adult dogs -that will tell you even more.
Funnily enough, my 2 most special current dogs both have a background of living in a flat. The oldest was one I bred and sold to an owner who lived in a flat. He's an extremely well trained and well socialised dog, in fact I've never had a better trained dog. He came back to me through no fault of his own or his owner's. He lacked for nothing and dare I say it is more relaibly house trained than the dogs I've had since pups. He also had a lot more walks in his previous home as he had to be taken out several times a day.
The second I bought from a breeder who lived in a flat. She'd not been socialised etc, other than going to the vet. Temperament is to such a huge extent genetic. This dog is my most special dog ever, she's just wonderful. Loves everyone, human or animal, not scared of anything. Even loves going to the vet. And everyone loves her in return.
Two extremely different breeds, they are in fact best friends and neither had any disadvantage or bad experience from living in a flat.
I'd be far more worried about buying a puppy that has been born and reared outdoors/in a kennel.