It is true that a load range E tire will tend to ride rougher than a load range D tire when inflated to the correct pressures. The problem comes in when you start towing. The D tire will indeed feel squishy and doesn't feel near as stable as an E tire will. I had a set of D range MTRs on my F250 for a short time, and while I was well within what the tire was rated to do with my trailer and load it wasn't something I wanted to do all the time. My current E range tires hold the load quite a bit better. Even on my F150 I ran E range tires and did not have the squishiness that my Ds on my F250 had. If you're that concerned with the ride then air the Es down to 30psi and it'll ride better, then air up to the rated pressure when towing.

 

Smart man. I back these claims with my own firsthand experience. OP let us know what you go with. My Toyo MTs are a E and look awesome, much more aggressive and capable in my eyes than the ATZ. Best of luck.