Almost 93K miles on my 6.0 and still planning on keeping it. Unscheduled repairs have run less than $4000 after eight years and this truck has either pulled an 11k lb tow hauler, ran winter mountain passes or carries my current combination most of those miles.
Some vehicles are more problematic than others. Once you lose trust in its reliability or the costs get to the point you could upgrade, it's time to get rid of it and start over.
When I am ready to replace my truck, I am not brand loyal. The manufacturers will have fight for my dollars and I will expect them to deliver their best vehicle from which I will choose.