DirecTV just sued Dish Network for false advertising as well over their "we are cheaper" ads from last year.
UPDATE: DirecTV Sues Dish Network Over 'Why Pay More' Commercials - WSJ.com
I've only owned DirecTV, but I use Dish Network a lot at a friend's house. I prefer DirecTV immensely more than Dish. There's little difference between the boxes, but DirecTV's customer service is the best I've ever encountered. Unfortunately, both have raised rates continuously year after year which can't be avoided. Locals are FREE on DirecTV compared to Dish too. It's expensive, but the picture quality on DirecTV is all mpeg4 compressed, which means far better picture quality than the mpeg2 on Dish or Comcast. The difference between them is
very noticeable.