You buy a diesel for the performance. THe diesel makes it power at lower RPM's.
In the end the diesel is providing more low end torque/power creating a more relaxed experience. The engine is not spinning as fast or revving as loud vs. a gasser. The transmission is not shifting or searching for the right gear.
The diesel is simply more capable when at the extremes.
If your only towing a few times a year on flat ground a gasser will be OK.
However if you tow regularly especially in hilly or mountainous terrain you will want a diesel.
The big three will all have a larger gas motor in 2020 which may change the equation going forward