I'll be shopping for a new (or new-ish) truck shortly for pulling a medium size trailer or 5th wheel. It seems like the vast majority of 3/4 and 1 ton trucks around here are 4WD, with jut a few 2WD...
It is difficult to find a 4x2 truck in a higher trim level around here. That is why I have a 4x4. In 10 years of towing my 34' 5er I have never engaged 4 wheel drive while towing. Have only used it in muddy pastures to our hunting cabin.