In 2012 we did a lot of research on the Big Three before buying our diesel. They were all so close for being reliable that I ended up with my F350 based mostly on the seating comfort.
I have never bought into extended warranties. Always thought they were a scam and waste of money. However, being full time and maxing our truck to its limits, I purchased one.
I have had 46,000 worry free miles from the 6.7. It is a BEAST and gets pretty good mileage towing.
Located an extended warranty for under $2,000 which will continue to take the worry out of towing almost all year every year.