I'm not a nut hugger to any brand truck, and could careless which one I own. I was in the same shoes, wanted a diesel to tow with and didn't know much. After a lot of reading I came to the conclusion a duramax would be my best bet for all around reliability.
I have a LLY duramax dually, I bought it a little over a year ago with 100k miles, it now has 132k miles. It gets regular oil changes, and fuel filters. Just had the trans fluid swapped. No issues out of the truck, other than a pulley and belt. It's a huge dually and gets 22mpg highway if I stay within 5 mph above the speed limit. Great trucks
Cummins motor is good, but everything else sucks. Suspension, transmission..