I agree with ducks4you that purebred dogs can have as many and sometimes more health issues than the Heinz 57s. I am 61YO and have only ever rescued my dogs and cats. I have also fostered several muttlies, including a whole litter of Lab/GSP pups. My lab was the only one we adopted as a puppy. He was found in an abandoned house. Probably pure lab, but who knows. He had hip dysplasia even as a pup, but lived a good life of 14.5 yrs. Second dog was a total mix with maybe some lab in her. Got her at 1 or 2YO, and she was better behaved and had a better temperament than the lab. They were quite the team and got along with each other and everyone they met, even kids. And we didn't have any kids for them to practice with... Now we have a rescued Coonhound, I would guess purebred Bluetick. He was 4YO and spent 3 of his young years in the shelter and foster home. He has a wacky personality, probably hound-related, but is the most loving dog. The other guy was 2YO when we got him and is probably Shep/Husky/Lab, also a great dog.
All this to say I will only ever rescue my dogs. I think you can get a good feel for their personality even from meeting them only once or twice, and personally I like the ones that are a little crazy.

I prefer older dogs to puppies because you can get a better sense of their personality, and I usually adopt from rescues that have the dogs in foster homes because you can learn a lot about them from the homes where they are living (good with kids, other dogs, cats, etc.).
If you have young kids, perhaps a puppy is a better way to go, but I don't see any reason to go with a purebred over a mutt. And for those who say mutts are too expensive, the expensive ones usually have had all of their shots and testing done, and yes have been neutered. The price you pay includes all of that. If you want a cheaper dog, go to a shelter. Most of the ones I have been to sell dogs for about $50.
I think from here on I will only rescue even older dogs. I am getting too old to entertain the younger ones!
Lester the Lab and Sophie the Lab? mystery mix
Woody the Coonhound and Cyrus the mystery mutt