3 dogs, a very good monitored alarm system, and guns available for close-in, perimiter range, and out to maybe 200 yards with nv. I'm about 15 miles from the nearest pd, and not too many deputies patrol at night.
Overall, a dog should be your first choice, if you have only one. Herding breeds tend to be the most protective in general. It still varies quite a bit by the individual pooch.
-hanko