If you are going to tow any kind of weight.9000 lbs or more the diesel is always the better choice.
I have an 06 and will never sell it because I don't like the emissions on the new trucks. The thing I don't like about towing with a gas truck is that you have to run them at much higher rpms when pulling his to make the power.
By the numbers I'm seeing on here a lot of guys are going by the over head. They are not accurate. I always hand calculate. My 06 gets 14-15 around town empty and 19 mpg on the highway. From what I hear the new trucks are a little less around town but about the same on the highway. The diesels can make much more power than stock with just a few simple upgrades.