Lets see, I've used both services so I'll tell you what I've experienced.
Dish Network, they arrived the afternoon we ordered it and did the installation. They charged us $40 a month for our package. Customer service was helpful if we ever had to call and the problem was fixed within a day or so. Returning the dish/receiver when we decided to switch... not so much. No one really seemed to know what they wanted us to do, eventually they decided we had to ship the receiver to them at our own cost.. nice of them.
DIRECTv, salesman carried on a spiel about how we would save so much money from Dish Network and that they would give us a free dvr that would only cost us a fee of $5.00 a month and could be used with any package. A call to DIRECTv got an installation truck to our place within a few days, bad sign although they could have just been busy.
We noticed that when the bill came we were being charged $10 a month for the dvr, not to mention the package we had chosen was also $10 more than we were told when we ordered it from DIRECTv. We only got a few more channels than when we did with Dish Network so we decided to switch to a cheaper DIRECTv plan, upon which we were told that the dvr would only work with *some* of their packages.
So basically DIRECTv was slow, charged more, and pretty much lied to us.
I'd go with a different company, any other company in fact.