Your dogs temperament should match yours. Do not choose a breed that is highly energetic if you are a couch potato. On the other hand, if you want a dog that will follow you everywhere around the house and who is always ready for a game of fetch or tug of war then you should consider a dog that is highly active and always has a lot of energy, instead of one of the lethargic breeds.
Though groups like the American Kennel Club make very specific designations about breeds and breed hybrids, there continue to be new breeds and breed variants developed all the time, as well as "up and coming breeds" not officially recognized by kennel clubs and experts. (Many dogs not purchased directly from breeders are also mixed-breeds of some kind, or have less than purebred ancestry.)
Keep in mind that large dogs are more expensive to keep. They eat more food, which costs you more money. Tick and flea preventives cost more for large dogs, as do other mediations.
Other breeding bills lump small breeders in with large commercial breeders. Small breeders are in no any way able to meet some of the kennel requirements written for large commercial establishments because they typically keep their dogs in their home as pets.