Worst compression
I have comcast cable and I would say all of them are poor. The HD channels seem to be better but on any given evening one will seem worse than the others with way more macroblocking and sound drops, screen freeze for a second or more. It seems to be random if its PBS, HBO, NBC, INHD1/2 whatever. You just have to hope what your watching is on a "good" channel.
I can't speak for anyone else. I would take less channels if I could have more bandwidth. For example I have 11 HBO channels. I would rather have 2-3 HBO channels with 4x the bandwidth. I'll happily take 100 good quality channels than 500 channels that look like poop.
P.S.A. Everyone buy an HDTV and demand content!