I used to have an Undercover hard plastic one. It was great other than it hanging over the rails. It was amazingly watertight, and you could stand on it if needed. I just didn't like the plastic dimpled look of it.
Now I currently have a Checkmate and it looks better, but it doesn't do to great at holding the water out. Does great holding it in, my Bedrug is kinda musty now.
If I had it to do over again I would find a way to smooth and paint the Undercover.
My Undercover is very watertight. The overhang isn't an issue nor is the textured finish. It's truly one of the best things I've bought for the truck. I can live w/the appearance if the function is outstanding, which it is. it's very well-designed, strong enough to walk on, and you can remove it easily-enough if you have to transport something tall. I can remove mine by myself, I use a couple of tiedowns to make it easier to do that, I loop them around it from side to side and use 'em as a lifting strap. If you had a garage you could just use a light block & tackle to lift it a bit and drive out from under it. You could do the same thing from any handy tree if you needed! Or, two people can easily do it in 2-3 minutes. Remove the front tab split rings, disconnect the struts' (no tools needed) balljoint attachment points, and lift the topper from each side.