Depends how much you tow vs how many miles empty IMO.
You know your next trailer is still within the capabilities of a good running 5.3 1500. For towing you can't go wrong with the 2500 though. Overkill? Not by a long shot.....for towing. Overkill for commuting? Only if the few mpg less with the bigger truck will cost you more than you think it's worth to have for towing.
^Totally confusing statements? Yup
Because either truck will do the trick for both duties. And neither will be bad at the one it doesn't excel in.
Still confusing? Yup
Get whichever one you want. Get the 2500 if you want more rock solid towing.