The 6.4 is a better truck, hands down, for many reasons.
The tuning potential is by far the best of any model from any maker. You can make these trucks fast, and bulletproof, for way less money than anything else.
Delete the emissions crap, delete or block the EGR
coolers, and put a tuner on it, and the 6.4 will make you a very happy man.
You can do all of this for around a grand.
You'd spend 3x (or more) trying to get a Dodge or Chevy that powerful, while still being reliable.
Have you driven them, checked out the interiors? I just don't see where the comparison is. I've driven them all, and the 6.4 is hands-down the best so far.