DCX, I have made a couple of copper cactus antennas and they work pretty well when they are set up correctly. Be shure to use a coaxial choke at the feed point.

A J-Pole is a half wave antenna fed by a quarter wave matching section. The radiation pattern is that of a half wave antenna and is symmetrical and doesn't need a counterpoise to work.

Steve does have a point though. If done right, a J-pole performs as well as any other half wave vertical antenna but I will admit that a half wave vertical dipole is easier to build and tune, and will work the same as a J-pole.