On my Tundra I got a Leer topper that was at the roof line of my truck. I got side windows that opened so I could reach things inside up front. When I locked the truck the topper would also lock automatically. It was perfectly matched to the truck, color and all and I really liked it. On some occasions I was unable to fit items into it because...it's a topper right? I bought it after a trip we made to Yellowstone. We had to keep moving stuff from the cab to the back when we would go somewhere and then stuff it all back in the cab again when we camped (bear rules).
When I traded for my F150, I went with a rollup tonneau cover. It's a hard shell that locks so it is more secure than the topper I had (out of sight out of mind). I can haul anything now but I lose about 1 foot of bed space for the roll part up front. Now when I go camping I can haul wood, generator and anything else back there and not worry about it.
Each has advantages. Also the Fords have much deeper beds in them so I get more room there with the tonneau cover.
2012 Ford F-150 EB 3.73
2015 Forest River 25RR
2004 Honda GL1800