If money were not an object, I would have diamond wire with a board and a strand of hot wire on top, or 4 board oak on 4 x 4 posts with a hot wire on top.
Since money was an object
, I have the 4 board on the road frontage, and high tensile wire on the other three sides. Six strands of high tensile wire is strung on 8" posts every 20 feet, the top and the second from the bottom wire are electric. This has the added advantage of keeping the neighbor's dogs out of the paddock. It's easy to maintain, decent looking and very safe for the horses.
Here's the thing about fencing - if a horse has good forage, water and companionship, you can keep them in with a piece of string. If they don't have those three things, you can't keep them in with a brick wall.
I know lots of folks rely on hot tape for fencing, but I would be loathe to rely on it alone. It's too easy for the fence to be shorted out, the battery to fall, a tree limb to fall on the fence .... It's great as temporary fence, or as an addition to a sturdier fence