I have a 2016 Silverado Crew 4x4. I towed an RV last weekend about 900 miles and averaged 11 MPG, probably driving average of 75 MPH. I'm not sure what it weighed, but I think it was rated as max GVWR of around 11k. I'm not sure what is involved, but it has Hill Decent Control. It will maintain a set speed I assume by downshifting and exhaust brake.
I used my friends F350 6.7l crew cab flatbed 2wd recently on another 900 mile trip. Overall noise from the engine was quite a bit more than my Chevy. Fuel mileage wasn't as good. Driving 75 MPH really got the RPM's up. And I was literally amazed at how often it went into regen.
I drove a 2008 Dodge 3500 2wd flatbed regular cab for a while. I never thought I would say this growing up, but I actually liked the Dodge...mostly. Turning on the headlights made a noticeable pull on the engine. I've heard another say the same about his. It had exhaust brake also that worked very well.
Unless Ford or Dodge have changed, a GM will turn quite a bit shorter due to a different front end configuration.
I definitely recommend a crew cab. Even travelling alone I find myself filling my cab on trips.
I've pulled lots of trailers over the years but never a RV until recently. Although it pulls with ease, I would probably go with dual rear wheeled 1 ton if I were to tow an RV regularly. The tandem axle single wheels on the trailer would wander depending on the pavement grooves sometimes and I noticed it more than I expected. I feel a 3500 would offer more stability.
For performance I think the GM has the others beat when towing. I recently read an article comparing them.
20 years ago you could not have given me a slipomatic. Now, an automatic is all I want.
Resale, I think a 3/4 ton will do better than the 1 ton just due to demand. I have seen a HUGE difference in used 2wd and 4x4. 4x4 is handy when needed, out of the way if not needed, and definitely will interest more people and bring more money for resale. Also, people now are almost all going for loaded vehicles. I'm not saying you have to get a sunroof or heated steering wheel, but leather and all power for sure.
If you are considering a new GM get a 2016. The 2017 will have quite a bit more power, but I don't like first year changes. If GM is changing for 2017 it may be stricter emissions so all the Big 3 may be different for 2017.