In the last five years, I've tried all three.
Dish Network programming is comparable to the others, customer service, including just finding someone to talk to, almost nil.
Comcast was fine, except from the time of purchase, the prices just seemed to creep up little by little, until, after nine months or so, I was paying an extra forty bucks a month on "incidental fees." The one plus is that if you bundle cable internet, it may be a decent deal, and the program guide is almost instantaneous. In my area, they do "throttle down" certain HD programming and sound, so you don't get programs broadcast in surround sound, or Dolby Digital, only in stereo 2.1.
DirecTV is where I've settled. Programming is fine, many packages available to satisfy the customer [which they all basically do anyway.] Sound quality is excellent for HD home theater viewing. Customer service is top notch. Price has not moved since day one.
The cons with DirecTV? Program guide is criminally slow, sometimes during data downloads, it hangs altogether.
As with just about any satellite service, and contrary to the optimistic advertising, weather will sometimes affect your viewing, i.e., heavy snow or rain.
Hope this helps,
Len