any terrier is a great gaurd dog. lurchers and pointers are not strong enough for fighting an intruder (the majority of intruders wont enter a property if theres a dog) but they wouldnt last long in a strugle. stafies, pitbulls, boxers,rotties,akitas all have powerfull jaw strenth and amazing stamina and also a better tollerance to pain hence the reason they were bred to fight.
if i was to choose a gaurd dog id have a german shepherd any day. well built, good stamina, intimidating looks, strong, and the instinct to protect people and property.