Unfortunately most people are far more likely to go on appearance alone. Size of your garden - should be large enough. Exercise - certain breeds require considerable daily exercise. Accommodation - A quality kennel is essential if the dog is to live outside. Some breeds are prone to constant medical problems.
Some breeds have high maintenance requirements with grooming and husbandry care.
Some breeds are prone to follow traits which, if not controlled, will lead the owner into conflict situations with other residents and Council. Jumping - containment problem. Digging - containment problem and wrecked gardens. Howler - conflict with neighbours. Aggression - containment problems, legal liability problems.