A pup from a poor quality breeder will come with hangups and gaps in its socialisation as well as potential health and welfare problems.
Many rescues have puppies and if a pregnant bitch finds her way into rescue, then usually she will have a 5* pregnancy and the pups will be beautifully reared by an experienced foster home. Hounds First for example have recently had two sets of gorgeous pups. Lots of pics on their FB page.
Rescue dogs are often a valid choice. Good rescues will make sure that a dog going to a family has lived with a foster family. The behaviours will have been assessed, the dog will have stopped growing so you know what size it is and you will have a good idea of training - what's been done so far and what you can build on. Rescue does not necessarily equal problem dog - in many cases dogs are simply handed in because of issues like divorce, emigration, family illness, job loss etc.
Whether it's a pedigree or a Heinz 57 - there is simply no shortcut to making your dog a delightful family member. Training is a lifelong commitment. But it's also the most amazing way of learning to speak "dog" and strengthening and deepening the bond between you. When your bouncy teenage Lab is towing you round the park, her training won't be any easier because she's a pedigree - you will still need to put the work in on developing your loose lead walking.
I've just come in tonight from class with my rescue lurcher. She's been with us less than a year, but four months after she was adopted by us, she was competing in her first Rally trial. She is an utter joy to work with - intelligent, eager to please and the most loving and adorable nature. I know masses of rescue dogs who compete at the highest levels of obedience, Rally, agility etc. Take a look at this year's Crufts Obreedience final for instance, there's a team of ex racing greyhounds taking part - all are ex racers, rescues and now enjoying a fabulous second career.
There are many, many rescues that will gladly rehome to families - most take a very sensible approach of tackling it on a dog by dog basis. Just off the top of my head, I can think of Wiccaweys, EGLR, Hounds First, Hope Rescue, the majority of RGT branches, GRW, GRWE, and many others. Hope are an excellent all breed rescue who insist on all dogs being in foster for at least a fortnight so behaviour can be assessed. EGLR's dogs are also all fostered before adoption and they have a handy list on their website allowing you to search dogs by suitability for children.