You lose nothing when deciding for an adult rather than a puppy. Our local shelters adopt out all the healthy pups they get. Mature dogs are often put down even when they're friendly, house trained and well mannered. There are an abundance of homes desiring pups. If you seriously want to save a dogs life by adopting at a shelter consider an adult dog.
Adult dogs are more loving than pups.
This is natural. It's an entitlement. Nurturing a pup is enriching, but the complex relationship possible with a mature dog is both deeper and more unique. Adult dogs are frequently easier. Less prone to chewing, jumping, and general mayhem, they're often more satisfying companions.