Been all around the Mulberry Bush on this one and here is our experience.
Had Direct TV, by far the best TV service we have ever had. Wanted to upgrade to HD when the new TV showed up, site line for HD dish was to low and could not get the signal.
Went to Comcast, paid a ton of money to have HD on only one TV (we had 2 other sets) Left as soon as we could. Comcast HD channels are just expanded SD shows (TnT, USA, etc) viewing is rediculous. The other two TVs were basic plug in the back with no box. It was going to cost us almost double what we were currently paying to upgrade with additional boxes. I don't even know how they can legally charge what they do.
Found out from a bird that Dish Offers TWO different Satellite pointing directions, Eastern Arc and Western Arc (the eastern arc points about 30 degrees further to the Southeast). We were able to get the Eastern Arc pointing (you have to request it when ordering the package). Have HD on each TV, have 3 times the channels than Comcast and pay the same amount. The only issue is that not all of the HD channels are on this Arc, we have lost Vs in HD, which isn't an issue if not not a house full of Hockey fans like us (TV size will compensate for this if need be, that's a free excuse for the guys out there, won't charge for it this time around
). NESN is still HD though, so all is well on the eastern front.
The HD picture with Dish, blows Comcast out of the water. 1080i from Dish matched with a 4,000,000:1 Contrast ratio on the LED and you can actually see the depth in the scene that was shot, like they are sitting on the couch next to you. Only slightly lagging behind Blueray, but oh so close. Took quite a while to get used to it. That is a pretty good picture signal if you ask me.