I would stick with a 2016-2018 truck. I think they look the best and they seem to be the last truck platform before we start to hit space age tech and what not. Saying that though a T1XX, 2019-Now, has some great engine and trans packages.
If you do tow your RVs I would definitely suggest buy a 2500 truck. Diesel is worth it if you tow all the time but if not then I would skip it. It seems the gasser 6.6L in the T1XX trucks is a pretty damn good engine.
If you go with a 1500 K2XX, 2016-2018, watch out for the transmissions. They are not that great.