Having owned trucks with toppers,and tonneau in the distant past. I am still getting used to the Monroe Aluminum Topper that came on my New-2-Me '13 F150. It was on it when I bought the truck and thought it a nice addition, but I am still depating on taking it off.
I like being able to haul items protected from the elements and being able to lock it. I also like the opening side windows, I can reach items at the front without climbing in.
I am not happy with the limited view out the rear window. Even with the side windows there is a big blind spot at both rear corners....and as previously mentioned with factory tinted rear glass on the cab and the rear window of the topper,night view is reduced even more. At night it's like backing into a dark tunnel!
Being aluminum it's very solid and light weight, but with that comes straight corners and sides. The new tuck shapes are full of curves. Since it meets at the center of the front,sides, and back, it extends past at the corners giving a slight gap . I see fiberglass toppers are molded to fit the contours of todays trucks much better.
I hated my old trucks tonneau. It was an early style vinyl one with velcro strips to attach it on the sides and tailgate. While easy to roll up and use the bed, it didn't last long and always came off the sides from the weight of snow, even after I intalled bows. But they have come a long way since then.