Do you believe fences make good neighbors? Or do you like having open spaces?

I ask because we moved into a house without a fence, and the older kids in the house next door have been an issue at times. They run around in our backyard and I've asked them to stay in their own yard, but I looked outside to find them and their cousins playing football using our newly planted trees as goal posts, grabbing the trees and shaking them. Not cool!