Cyberonic: good service, but had to disconnect
I only had good experiences with their service dept. I always got through within a minute or so, and they were always friendly and helpful.
The only reason I disconnected with them was that I had DSL, is that I was far away from the switch and my speed was low. The quality of the wiring down the street and into my apartment, which they have no power over, was also not great, and they had to cut their speed to below 1Mps to reduce error rate. Too slow to browse anything dynamic on the web, and nothing they could do about from their end.