I had a Zero Gravity screen on an '01 Gixxer 600-- Didn't think it was all that great. It was fairly thin and brittle looking/feeling. The bike came with it. It did look nice, though, with the Dark Smoke finish.
I like Puig screens. They are much thicker and durable than ZG's. Unless you're a racer concerned about saving every ounce of weight possible, I would think Puig screens are a better bet... Not that they feel heavy anyways.
There are a few different screen styles from them: Standard, Racing (Double Bubble style), and Touring (has a lip at the top of the taller screen).
They also come in Light and Dark smoke, Clear, and a variety of colors.
You can find these screens at your local Cycle Gear, if you have one in your area.