We have used both satellite service providers over the years and both offer pretty much the same programming. Never paid any heed to where their satellites flew in the horizon, didn't even know it was an issue as we found the process for manually acquiring either satellite service when RVing to be quite similar for the last dozen years or so.
From an RVers perspective, one must decide to manually point or go with an automated acquisition system. No automated domes whether roof mounted or portable can acquire Directv HD programming, Dish network HD is attainable. For automated Directv HD access, a roof mounted Winegard Traveler runs about $2K installed.
We are currently with Dish network because they have specific sports programming which is not available on Directv at this time. Other than that we have no real allegiance to either, price of the programming usually dictates which service we have and is the main reason we change satellite service providers every few years.