I have a 2017 F250 6.7 and love it. I upgraded from an '08 F150 primarily for a newer vehicle and to also tow our 30' travel trailer easier. Night and day difference for towing, not just the power of the diesel, but also just how the truck feels more in control of the trailer as opposed to the other way around.
With all that said, if I could do it again I would have gone with the F350. The only change is really a slightly heavier-duty rear axle and an extra leaf spring (MSRP used to only be about $900 difference). BUT, you get a door sticker that allows for heavier towing. Yes the F250 can do pretty much everything the F350 can, but the sticker will say different, and if you ever were in an injury accident or worse while towing, you could get sued into oblivion if you are over the sticker weight.
Part of the issue with my truck is that the 6.7 diesel is ~1000 lbs heavier than a gas engine. It pretty much makes towing a 5th wheel or goose-neck trailer not an option. I would like the ability to upgrade to a 5th wheel, but I really shouldn't with my truck. Most 5th wheel RVs will have a pin weight higher than my sticker shown below. Going with a gas engine negates a lot of this - not all of it. In summary, go F350 - resale is higher because of the above also...