There are two kinds of people in the world: small-dog people and big-dog people. And while some people might be happy with a dog that weighs under 5 pounds and fits in a handbag, I want my canines big enough to pull a broken-down car and then knock me over for a cuddle. But the largest dog breeds, in addition to being ginormous baskets of floof, come with a host of myths and misconceptions about them. Your Great Danes, your Newfoundlands, or Afghans are not very well understood.
Larger animals do often need more space and won't necessarily flourish in apartments or cramped living conditions. And they're often more expensive than some smaller breeds to insure, though that changes depending on their parentage and hereditary health conditions. But they're not innately more "difficult" or aloof because they happen to be bigger. Large breed dogs, like all dogs, require training, particularly because their strength means they can disobey you if they want to. But if you want a big beautiful friend in your house, and don't mind if it occasionally competes with you for the couch and wins, then it's time to clear the air and get a few misguided ideas about big dogs out of the way.