I don't think you can go wrong with any of them. My FIL has the Chevy 6.0 and loves it.
My buddy has a Ram 6.4 and is annoyed by the transmission, but it hauls his 5th wheel up the mountains of western PA just fine. He doesn't like how/when it shifts going up elevations, but he gets to the campground just fine every time. You can also get the 5.7 Hemi in a 2500 and they put out pretty respectable HP and torque numbers.
I've never had or driven a Ford 6.2, but its a drivetrain that has been around for some time now and appears to be pretty solid.
As far as I know, there aren't any real issues with any of them.