From a survival/preparedness point of view a dog offers a series of advantages that should not go unnoticed, yet at the same time we have to consider the disadvanteges as well.
Feeding a dog during an economic downturn can be a problem. Proof of that is the ammount of abandoned expensive dogs we see in cities becuase of the crisis. At the same time we may want a dog for security and need a certian size and intimidation factor which the smallest pets will not deliver. Their keen senses alert them and they can bark so as to warn you but sometimes you will want a dog criminals will have respect for.
Maybe their most important real world role, a dog means fun and entertainment for both adults and children. At the same time a needy dog will take up more of your time. A dog that sheds too much hair will also force you to clean more if it sleeps indoors.
For these reasons I feel that a Bull Terrier is an interesting alternative, mostly for people with time and space restrictions, a good comprosmise between feeding costs, intimidation and friendlyness towards kids.
The Jack Russell is also an interesting choice, especially if small game hunting is in the picutre, but it lacks the size for a security dog.The Bull terrier isnt very big, but still big enough o bite and scare would be robbers.