Chevy wins the tests because they buy the most ads. It sounds like your truck might be worth more to others than yourself. There are lots of threads at Fordtrucks.com that give examples of very bad dealers with respect to working on the 6.0. It isn't a typical Ford engine. It sounds like you've got one of the clueless dealers. On the other hand, the 6.0 has very known issues with known solutions and preventions.
If you are buying new, I think any can be good choices. I hear you'll get the best deal on a Dodge since they aren't as popular.
If you are buying used, I'd research a good shop on Fordtrucks and get an estimate of the cost to fix your truck to give you confidence. Weigh that versus the cost to trade.