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...
I had a 2wd with our first trailer, rain came while camping and when we went to leave I had to have a tow truck get us out. Cost of the tow was about what it would've cost between 2wd and 4wd. Fast forward to last year, same thing but different trailer and truck. This time all it took was a turn of a switch and eased on out. Worth every penny for 4wd!