A neighbor of my parents has an '18 Tundra, he pulls a 26' 5th wheel and blows by all the diesels that are pulling a similar weight. I didn't like the front end of it at first but it grows on ya.
There is more to towing than just engine performance. According to one RV website, 5th wheel trailers can weigh 8,000 to 10,000 pounds (23 - 30ft), so while the engine might be able to take it, the frame, brakes, and bearings are not made for it. Plus, it is illegal to tow more weight than what a vehicle is rated for; and, if you "upgrade" the truck to tow that much (air bags, heavier sway bars and frame stiffeners), you still have to get the truck recertified before you can legally tow with it.
The EcoBoost is a beast. I have a couple of family members with them. Impressive motors.
But as far as reliability goes I would put my bet on the V8 being longer lasting with less issues. We all know the inherent issues caused by turbo engines. That might just be my fear of "new" technology though.
That is my biggest worry. I tend to keep trucks for a while, and this one will be no different.
What about the Nissan Titan xD? The Cummins diesel is a workhorse or you can get the V8.
Personally, I'm a fan of the RAM 1500 - the new 2019 Rebel looks badass.
I have looked at the Titan, I like the look of the truck and that bed system Nissan has is pretty cool. The zero-gravity seats provide the most comfortable ride of any larger pickup. Power-wise, the V8 isn't bad, but the for the money the towing specs are lackluster compared other trucks in the class. I have read five reviews (major car/truck magazines) on the Cummins, and all of had major issues with that motor starting around 10k miles, most dealing with bellowing white smoke coming out of the exhaust and the truck loosing power while towing.
I have looked at the Ram 1500, and yes the Rebel looks cool, but if memory serves, it was made to rival the Raptor, so it is rather light on its towing specs compared to other trucks.
Awesome input guys, and I am still searching. Because I do keep trucks as long as I do I am trying to load my next one up as much as I can out of the gate. Because of this, my financial manager (wife) and I are having some disagreements on price...