One thing to keep in mind Jonathan, don't get too caught up in the breed. Yes some have a natural tendency to have certain traitors over others, but they are individuals. Each can have its own 'personality'. I've had several dogs in my lifetime. Some pure breads and some mutts. I think the way you raise and handle them makes more of a difference than the breed. As Maverick said, they are social animals and they are a sponge absorbing how to fit into your world. With some training you can make almost any dog a good watch dog and protector. Rite now I have three mutts rescued from the pound. One a large mostly pit, a large mostly collie, and a small pit that thinks it's my child and sleeps in bed with me. The collie is true to its nature and is a really friendly dog that loves people and attention. The large pit is a lot more reserved with people, but loves the family. It is smart to get an animal that's got a natural inclination to do the job you want, as it will be easier to train them. Just remember though, a good trainer can get any dog to understand what you want it to do.