Sattelite has the potential for being better quality, but that's only under perfect conditions. Digital cable is more consistent.
Last night I got home about 6pm, there was a DirectTV tech installing satellite for the people next door. I went to bed at 11pm and he was still out there working on it.
My roommates and I decided to upgrade our digital cable package, and it took about 60 seconds on the phone before the new channels appeared on our TV.