I can't offer much input for the Zowie or QPAD, but I can tell you to avoid using the BWU. It is not at all worth the cost. Not only does it feel cheap, but mine has began to fail. Certain keys just no longer register without repeatedly pressing it. I've had it for just about a year now, and I took excellent care of it. Never traveled with it, kept it clean, never ate or drank around it. It's obnoxiously large (which is just a personal peeve), it feels awful, the gloss is annoying, the keys are very low quality, the LEDs have failed in several spots, and it's very difficult to get in to if you want to try to fix something yourself. If you are going to get one, you should invest in a warranty. Personally I think it'd be better to spend the money on a higher quality keyboard like a Filco, Ducky, Leopold, etc.
In short, stay away from the BWU.