Out of all the size categories, large-sized dogs have the most dog breeds in it. This is of course, owing to the fact that it spans the biggest weight range of 50-100 pounds.
The bigger a dog is, the more responsibility a dog owner has to take good care of their canine friend. A large dog can be twice the excitable and lovable fur-ball than a smaller dog, but also twice as messy and destructive if it decides to chew your pillows or potty on the floor.
With a large dog, obedience training is an absolute must. A disobedient and uncontrollable large dog can pose a legitimate danger to yourself and others, especially in public areas.
The costs of owning a dog increases the bigger they are. Bigger dogs eat more food, make bigger messes, and any veterinary procedures cost more because they are more difficult to keep calm and need higher doses of anesthesia or other medicine.
Large dogs also tend to have boundless energy and require lots of exercise. Some breeds are more mellow than others, but you have to be willing to take them outdoors to stretch their legs just in case.
Some dogs shed a lot and require lots of grooming, while others are lower maintenance. When adopting a large dog, be very careful that you can handle the many responsibilities needed to take great care of them.
Check out the overviews below to get a better idea.