If you have a large tract of land -- even moderately large -- get a pit. They're reliable working dogs. If you don't, get an am staff. They are considerably more amiable around other dogs. They aren't bred for game. They are show dogs. As a result, they aren't working dogs. The aren't designed to move far and fast. If you're sure you'll need the dog to work, an am staff isn't what you want. A pit can cover a great deal of distance everyday. They are very intelligent and enjoy working. On the flip side of that, they require a ton of exercise. Not a good dog for someone living in a city that isn't highly motivated to exercise the dog.