Diesel if you don't mind the noise and chatter. Of the two I'd go with the cummins. Not exactly small.
As an auto tech before my current occupation, (and a GM guy) I am impressed with that Ford 5.4L. I don't believe that 4.6 is available in the 3/4 ton but I definately would not rec'd that motor anyway.
Chrysler hasn't convied me to even consider buying a rig from them.