Again, these "which one" questions get to be "I like this one" and it then becomes a personal preference thread. I have both. Directv at home and Dish when camping. I ended up with Dish in the trailer because Direct has no HD for RVs, unless you want to try setting up a tripod or have a roof mount. None of the portable receivers for Direct give you HD. Having a roof mounted receiver means that I have a limited choice of parking spots in an RV park or in the forest. A forest has lots of trees as do some RV parks (in Arizona you want trees for shade all year around) that makes roof mounted antennas worthless.
Having a tripod, from my past experience is a major PIA. Some will jump in and tell us how easy set up is for them. Sorry but it is a PIA. And if the wind blows, like Kansas or northern Arizona where I hunt in the spring, forget keeping it on target. So, I have a Tailgator that I set out, hook the coax to and start the TV. I am watching TV in a few minutes and can park pretty much where I please without signal interference.
And the final note. I have had Directv for about 10 years now. They do raise prices, and it is annoying but each year I call them, tell them I don't like their price increase and will move to Dish if it keeps up and they knock $50-60 off of my monthly bill. Right now my bill has a $60 reduction on it for the next year because I bothered to call them about it. A lot of companies will do that if asked.