Comcast used to be evil, but they have really improved in my area. My connection used to drop me every hour or so and I would have to reset my modem (tried new modems and a dozen of comcast techs came out to my house over several months and said that it was the houses wiring that was bad and there was nothing they could do unless I ran new cable myself from the pole to the modem). My digital cable used to suck and lag (black boxes appearing, static, you name it).
But... then came Katrina.....
Katrina destroyed all of the comcast lines in my area and comcast had to run brand new ones. They restored cable TV and internet before the phone company restored phone service here.
Since Katrina forced them to put up the new lines, I have had NO disconnects, downtime, or problems with digital cable quality, the speed is even slightly faster.
I guess it was not my houses wiring after all.
My friends (in the Jackson area of Mississippi) have told me that Time Warner is horrible in terms of service quality. But, I cannot comment on them for I have never had them and its not available in my area. Comcast rocks 😀
But, I think it all comes down to the people running the cable provider locally in your area that is the final say in service quality.