I've experienced both - Directv is better IMO. I can't preview a channel on dish in the left hand window. You have to press enter on the channel clicker to watch a channel, so flipping through many channels and stopping on one won't allow you to see it live.
Also Directv has an integrated Tivo unit which gives you more features than an addon retrofit unit, which is all you can get from dish.
Also, the numbering of channels on Directv is MUCH simpler 100's are your PPV, 200's are your discovery and news channels. Your 500's are the premiums, etc. 600's are sports. 800's are music, etc. Dish has four digit channel numbers and it's more difficult to keep track of what block of numbers correspond to what types of channels.
Plus with directv you have competing companies driven to make better receivers with more features b/c of competition. With dish, you get it from them and you get what you get.
Directv is far ahead of dish on HDTV and especially sports. I'll take DirecTV over dish anyday of the week. BTW, don't worry about a torrential downpour cutting out your satellite. I had cable and it was down for days at a time everytime I turned around. Adelphia really sooks.