What predators do you have?
Most will be deterred by the electric wire. I run two wires, a foot and three feet off the ground, around my pen and coop. I keep dabs of peanut butter at regular intervals on the wire to "condition" any curious predators. This invites bears, foxes, raccoons, dogs, etc, to smell with a wet nose or taste with a wet tongue and to get the "message".
I also buried the fencing in the ground, angled outward, a few inches deep, with flat rocks on top. The pen is also covered so no birds of prey can get in.
But the electric wire is the thing that has proven to give the enclosure the most security. I know it works because one morning I found bear nose marks on the glass door of the coop, and it abruptly stopped when it got to the wire. There were no second tries.