We went with the Trac Rac tonneau cover. This is the only system that we could find that incorporated both an tonneau cover and rack system. The Trac Rac tonneau cover is similar to the Truxedo.....it is a vinyl roll up cover held down by velcro. It rolls easily to the front of the bed, leaving unrestricted loading for mulch, moving furniture, etc. If you have a locking tailgate, then you can't open the cover either........unless you have a pocket knife.
Wet traveling will get stuff near the back of the bed wet, so you have be careful there. If you have a plastic bed liner (without front drainage) and the truck is parked facing downhill, then water will puddle in the front of the bed during really heavy rain.....gotta be careful with that.
We can load up everything we need for camping under the tonneau cover.....firewood, toolboxes, extra water, scuba gear, Big Buddy Heater, etc., and it works out great. I have a couple of Yak racks with Copperhead bike racks mounted to the tracks on the bed rail, so the bikes ride over top of the tonneau cover. The canoe goes on the Trac Racs, over top and to the side of the bikes.
Tonneau cover pros: Easy quick bed access when needed. Looks good. Increases gas mileage. Keeps things from prying eyes.
Tonneau cover cons: Vinyl ones can be opened via a pocket knife. Allows some water in.
Topper pros: Secure. Very little water infiltration. Can hold more gear. Maybe increases gas mileage.....better aerodynamics vs. the weight ??
Topper cons: Gotta remove that puppy to haul anything. Limits "over the shoulder" visibility. Gotta crawl into that thing when you need something.
Our system works great for us, but might not for the next camper. Ain't this forum great for finding out this stuff???
Chap