It's really not about the dog, a CKC dog is just as good as an AKC dog, and both are just as good as the mutts you find at your local pound. What most people don't understand is we have an abundance of dogs right now, millions of dogs are put to death yearly because breeders breed indiscriminately without knowing what the market will bare. Buying a purebred should be about loving a specific breed so much you want to see the breed preserved in the future and this means you want to support the best breeders who will sell you a dog. So what you are doing is supporting good breeders, not buying a dog. Most reputable breeders do register their dogs with the AKC, this doesn't mean that all AKC breeders are reputable, but the registry itself is more reputable than the CKC, which in my opinion is worthless. If you want to increase your chances of getting a healthy dog that looks like a yorkie, find the best breeder you can find. You'll have your dog around 15 years if your lucky and paying a little extra to a good breeder is well worth it. Here's some information on registries.
Registries By the way, the Canadian Kennel Club (CKC) is the Canadian registry comparable to the AKC, however the Continental Kennel Club (CKC), an American Company, is considered a paper registry, and even it's initials were used in an attempt to mislead people.