I like the Boonie style hat. I've worn a waxed canvas one for years but just updated to the Cabelas Gore-tex. the back side of it can hit the top of my pack when I'm packing in, but it is more flexible than the rigid brim hats so the back of the brim can be folded out of the way.
Can also still be worn under a rain jacket hood if needed.
I hate the noise a boonie makes when it rubs on my pack. I've switched to an OR ball cap style hat that has a removable clothe that blocks the sun from your ears and the back of your neck. I also like being able to just pull my hood up over my hat.