We have a wireless that works great, for us. I say for us because it only works in a circle. But if your boundaries are such that you can make it work for you, it's great. We laid the wire on our first one and it was a pain in the ass. Got accidentally dug up, cut and chewed through. Had to retrain dog each time.
As has been pointed out already, the training is critical. Probably more so than the fence itself.
Also, don't leave the collar on during a thunderstorm! Dog can get zapped.