Roof material on a greenhouse?

We moved to our farm last year, and there is a "building" that seems to have been used as half firewood storage (metal roof/walls for that part) and half greenhouse (glass panels for walls). The greenhouse half currently has no roof, and only a couple 2x4 supports in the roof, and I think it must have been covered with plastic. I was thinking of getting polycarbonate corrugated panels to cover that area, since I want light to come through, but I'm wondering if there are better choices. What all have you used and been happy with, or used and not been happy with? Thanks!

I don't know of anything better than the UV stable poly carb. It's so durable. Maybe bullet proof glass?

And if you are in a southern climate as we are, we painted the high portions of the clear panel with white to lower the solar gain we also use a heavy shade cloth in summer.