Depends on what you haul while camping or at other times. I tried a tonneau cover but with fire wood, chairs, pop-up canopy, cooler, 5-gallon water jug, fold-up table, corn-hole boards, and seemingly the kitchen sink, I couldn't fit everything under the cover. I went with the topper (or cap) and racks on the topper for my canoe.
The topper also comes in handy during huntin' season for me and while fishing. Allows me to keep some gear in there out of sight and the weather.
2016 Flagstaff 23LB