There are advantages working for both companies, you need to look at both side by side and decide which is the best for you.
The one thing that will surprise you is how many customers will get a new installation from you and will not pay their bill or cancel service over no reason what so ever. The chargebacks suck in this business!
I believe Dish is going to pay you better, but the issue is the equipment liability. You install a system for a customer and they don't pay the bill within 180 days then Dish charges you back on the equipment and you got to go after that customer to retrieve it. Directv on the other hand pays less, but if they don't pay their bill Directv will just send the customer empty boxes and you do not need to go out there.