you have to check your channel preferences and look for the best available package from all the dth services. The viewing quality of every dth is same.
So now we are left with only one thing and that is how easy the software of your STB is. For example i really hate the software of Dish TV, its unusable for me. Also check, many STBs take 2-3 or more seconds to change the channel.
I personally like Airtel for the single most reason of the unified remote they provide.. so you dont have to use two remotes (tv+stb). Secondly their customer care is very good.