Since you arent sold on a make yet, or gas or diesel, it might make sense to concentrate on the trailer weight and the GCWR of the various trucks available, and factor in how much actual towing you will do under what conditions and what else you are using the truck for. Otherwise you’ll end up buying a very capable, very expensive tow vehicle that may be more truck than you need or want.
I have a 2017 Ford 6.7 diesel. I’m thrilled with it and it does everything I need. Its also way more truck than I need these days since I no longer tow heavy (loader landscape on an equip trailer - around 18K lbs) and cost a lot for the use I now get out of it. I’ll keep it because I like it, but if I were doing it again, I’d go for the Ford 7.3 gas with the max towing/payload I could get in an F250. That way Id have less invested and a very practical, enjoyable, everyday truck with decent ride comfort that can do the occasional heavy lifting as necessary.