I've put a lot of thought and research into this myself, since we are in the process of building a new house on new property near a wilderness area. What I've heard from others is, install mesh fencing to create a physical barrier, and place one or more strands of electric fencing along the top, rated HIGH shock. Miniatures won't be able to reach it so won't accidently get shocked, but any predator that tries to come over the fence will be (hopefully) deterred. Although, for cougars (also known as mountain lions) I've been told that you really need an eight foot tall fence with electric on top. That isn't feasible for a perimeter fence for most places--imagine the cost!--- but I'm strongly considering it for at least some of my "run out" areas near the barn, especially for mares with young foals.
Also, for livestock protection, (because some determined predators WILL make it over the fence if they want to badly enough) I've decided that my main protection will be livestock guardian dogs. With llamas or donkeys, you just don't know if they will guard, and since they are "prey animals" themselves, there is only so much they can do. I want one or more huge dogs out there, audibly warning away predators and able to fight if necessary (though me and my gun will be there for backup.)
Predators will go after the easiest prey possible, so if you make it as difficult as you can for them to reach and get to your horses, they will look for an easier meal.
Oh and my horses will be stalled at night for safety.