You really can't go wrong these days. All 3 manufacturers make some really nice trucks. The main thing that set the Ram apart for me is the coil rear suspension. It's a much better suspension as a daily driver and for towing IMO. I also like the cylinder deactivation to help the MPGs a bit. I also found the Ram to be a few thousand cheaper for a similarly equipped truck.
All that being said it was still a very close call for me when I bought a couple years ago. Like every time I buy, the trick is lots of research both on the computer and at the dealers sitting/driving the trucks.