I mostly use a cotton hat with an internal mosquito net. I`ve waterproofed it with wax. I bought it in Finland four years ago. Really neat idea, looks better than my old hat with the net on the outside. The one on the right on the picture.
With the net in action (I rarely use it though).
The reason I like cotton hats is that they could be stashed in a pocket or ruck without loosing its shape.
Tor
What a clever idea
I'm surprised they're not more popular