I don't mean to be dismissive of rescues. We are currently on our fourth and all have been positive experiences. The one problem was the one we had the longest, and she was clearly abused by a former owner, who was a man, and she was initially so jittery around men that she would pee instantly. Well, we got her comfortable enough to mellow out over the years, but as she aged she started to develop a mean, uncontrollable streak that would show in a flash, and then disappear for weeks. And then she suffered incontinence, apparently because the shelter from which we got her didn't do a great spay job when we adopted her. So...with a young baby and a neighborhood filled with kids, we had a dog that could snap with no notice, and which started peeing in the house daily, and incurably. We had mostly positive memories of the nine-plus years we had her, but these were now serious problems. And we knew nothing about the breed mix (Dalmation mixed with Short-haired Pointer, maybe?) or her history, so it was not a good situation for us.
Coming off of that, I wanted to have more control over the choice the next time. We tried being very selective with rescue options and after several months it just wasn't panning out. Here's a newsflash: people rarely abandon great, young dogs. There are a lot of great, old dogs available. You think you're spending a mint buying a pedigree? Try paying for animal health care. Think your kids got sad when they learned that mom and dad are Santa? Try consoling them when they learn of a dying/dead family pet. All I'm saying is that each dog comes with issues. With most rescues, especially young ones, it's the crap shoot of never really knowing what you have. With the old ones, it's the probability of health problems and death. With puppies, it's training and housebreaking. My conclusion was that the puppies of known origin were the best bet, because the bad part comes at the beginning, and because it pays dividends in the long run when your dog knows you better, and you know him/her better because you've been there from the start. So, for once, we went with a reputable breeder and picked our breed and dog.
That said, we've had two other rescues/adoptions since then, both older dogs whose owners could not care for them any longer because of incapacity/death, and both have been very good experiences. But no matter how much work you do trying to temper expectations, if you have kids they will likely be devastated when the dog dies.