What Type of Dog

Dogs are companions. If you want one just as a guard, buy a burglar alarm. Dogs are usually effective burglar deterrents, whatever their breed, but their first function in a home must be as a friend - and there is no better friend.

They don't criticize you (or not too unkindly), they don't sulk (or not for too long), and they are always there to comfort you and love you.

Choosing the right breed is an intensely personal matter, but there ITS broad guidelines.
The size of the fully grown dog is important, but perhaps not quite so critical as it may seem.

Very large dogs need a lot of exercise, and once you have decided that there is room in your house for a large dog, exercise is the most important consideration.