I have the latest HD equipment and programming from D (7 yrs), E (10 yrs) and Charter Cable (5yr). Why? Because each offers something I want that the other two do not provide. If I could keep only one, it would be E. The reason is the equipment - it's much better than the others. In the end, the programming will end up about the same (except for D's expensive sports package), so for me it's about how the the programming is presented, i,e, the responsiveness and layout of the guide and menus; dvr recording and playback options; video quality, video output options including Pip/Pop built into the receiver; OTA built in; and reliability/service. E leads or is equal in all these categories in the dealings I've had with all three.
They are equal in that they each have very little down time. In fact, E called me and ask if I was having a problem with dropouts. I wasn't, but they said one of my dishes had a problem (they monitor performance) and they came out and replaced the LNB.
None are perfect, but if E has (or is likely to get) the programming you want, and your list of desired qualities is similar to mine, I think E is your best choice.