They will all work initially but how long will they last? I would stick with the dogtra if you want a wire fence - It runs about $250.
Sportdog also makes a decent unit but the quality overall is a little less than the dogtra.
There is a new e-collar out that will also work as a containment system using gps - it is about $600 list - it will eliminate the need to lay a wire barrier -
and will work as a training and tracking collar as well. It is made my Dog Expedition (an off shoot of DT systems) It is called the Border Patrol
I havent seen or used one yet - we just got product info on it a couple of weeks ago.
Good Luck with the project.