I can only speak for chevy trucks as thats all I have ever owned. 1969 chevy with 283, 1988 chevy w/350, 1996 with 4.3, and 2006 with 5.3
I have the 4 speed so trucks have come a bit up in design with the 6 speeds.
Because I have never had major mechanical issues with my chevys I would never look elsewhere.
Fuel pump, water pump, batt, alternator, and a radiator on the 1996 are about the extent of my maintenance. ( had 163K on that 4.3) Other trucks no issues the time I owned them.
The 2017 chevy I would get with the 5.3, 6 speed, and max tow package with the 3:73 rear.
That truck in 4wd will have a 2100 lbs payload and tow to 12000 lbs.
It will have 355 HP with 383 tq @ 4100 RPM.
The 6.2 IMO would use too much gas. As you stated only 10% you will be towing.
With my 2006 4 speed towing in 3rd gear I average 9MPG @70MPH with a trailer weight of 5500 lbs. combined 12K lbs or so.
The only good a turbo ecoboost or turbo diesel will net you is better high altitude towing if your in the mountains all the time. Power of the engine is not reduced per se"
Chevy is tried and true IMO. Ford keeps changing their designs..  Often many issues come of it. Spark plug blow out years, bad diesel engine design some years, cam phaser issues now, and the ecoboost motors having carbon issues.
Rams coil spring suspension and trans issues were/are common.
All my opinion is all.