I have a gen. 3 Ram so no photo but I recommend a cap that has a sharp angled flange or lip that extends down past the deck of the box where the cap rests and seals. The flange must slightly overhang the outside of the pickups box, instead of the cap terminating with an almost square outside corner and flat bottom on the bed rail.
The problem with most cap to box mating surfaces is water surface tension. The sharp angle of a Leer cap is the solution, which allows water to drip off the side rather than clinging to the underside of the cap and running downhill until it finds a way around the rubber seal. Even with a perfect seal, it can run downhill to the tailgate and usually some of the water finds a way in there. I've seen this feature in cap other than the Leer. I don't recall but maybe Gemtop was one of them, but I think Gemtop is out of business now.
I learned the hard way and for for years I've thought of adding a fiberglass extended flange to my cap. Now that the paint is getting pretty old, I'm think I'm getting close to doing it.

BTW, I have tailgate seals too, and they only get you so far.
I have no interest in Leer, other than I regret that I didn't pay a little more and buy one!