You have asked a simple question that does not have a simple answer. It depends on the quality of your cable signal.
Cable signal quality on the analog channels can vary between the various cable companies. It will also vary between different cities, between different neighborhoods, and even between different houses. Before switching to satellite I had the opportunity to compare the picture quality at my home with my next door neighbor's and there was a big difference.
Satellite TV has the advantage of providing a uniform picture quality across the country.
My best suggestion is to find a friend/neighbor/relative who has the satellite system you are thinking of getting (either DirectTV or DishNetwork) and get them to let you try their system for a while. Barring that visit a dealer/retailer with a demo unit of the system you are looking at.
The question you asked calls for an opinion. Different people will have different opinions but the only one that counts is yours. So get out there and form your opinion!
Since you asked though here is my opinion. I find that over compressed channels on DishNetwork have a soft, slightly out of focus quality, but to me this is better than the snowy/ghosted picture that is found on my local cable system or by analog OTA. The digital OTA channels I am able to receive however blow the doors off of all competitors.