The Nexens on the HD trucks are garbage in my opinion (as are most tires that are installed from the factory). All of my previous Rams had them on and all were swapped for better tires. Prior to my current truck I swapped them all to Cooper AT3s but there are many good tires available.
My current Ram has Michelins on it and I like them better than the Coopers (for highway tires).
Rotation could be part of the issue on the DRW trucks though. A lot of tire places only rotate the outer 4 to avoid breaking down the wheels. Inner tires must move to the front, fronts move to the outside rear, outside rear move to the inside rear.
I use Discount Tire for all of my tires, rotations, balancing, etc... Duallys do require rotating all 6 tires and to do it properly 4 of the 6 must be dismounted and remounted on the rim. I use DT because they do this every time. I would suggest that you find a tire shop that does this on any tire you choose.