jjanj,
I made the switchover in September of 2007, and while no service is perfect, I have been very satisfied with DirecTV and would not go back to Dish.
My major reason is why I watch TV: programming. Dish's business model seems to be "let's see how little we can pay providers for programming." As a result, they seem to get into constant retrans arguments with national providers and local stations, and the viewer is left staring at a blank screen for days and weeks while Dish plays its little games of brinksmanship with the providers.
On the other hand, DirecTV's business model seems to be, "we'll pay what it takes to secure programming, and pass the costs on to the customer." This makes DirecTV a more expensive proposition but a more reliable one, in my opinion. Barring a change of ownership I can't see Dish ever securing premium sports packages such as MLB Extra Innings or NFL Sunday Ticket.
I will say that DirecTV is not above gouging customers, particularly on Sunday Ticket. Unless they change their arrangement, if you want to watch SD in high-def you must get the SuperFan package and spend another hundred bucks on top of the Sunday Ticket subscription. That's not right, and it's why I won't renew SD for '09.
Everyone will have their own reasons for subscribing to a particular service. But as I said, considering the major reason I watch TV is the programming alternatives, I am content to stay with DirecTV when my contract expires this September. Good luck!