Adult dogs require less care than puppies. Older dogs may have developed some behavior problems and can be difficult to train. Puppies are fun and easier to train and socialize, at the same time require a lot of care. If you are inclined to the adult dog, consider a rescue dog. There are breed rescue groups who often can direct you to a dog of your favorite breed who badly needs a home.
The dominant pup of the litter will usually be the first to approach you. This puppy will probably be difficult to train and discipline, so if you are inexperienced, it would be better to select a different one. Avoid also a pup that is extremely shy; it may be difficult to socialize. Also avoid the runt of the litter, who may have serious health problems in its future. Stay away from shy, whimpering, fearful puppies, puppies with dull coats, crusty or running eyes, signs of diarrhea, and rashes or sores on their abdomens.