I personally have experienced a taste of both Time Warner as well as Cablevision and my opinion is that Cablevision is overall an inferior company to Time Warner collectively, not just on cable TV service.
Lets not forget that Time Warner has its own news service, NY1, to counter Cablevision's News 12. I didn't think News 12 was too shabby though, probably one of Cablevision's better efforts. Time Warner does offer more public access channels though as far as I can tell, at least in their Queens system.
One telling difference between the two companies seems to be their high speed internet service. I've had Roadrunner at home for five+ years with, as far as I can recall, three outages. When I was away at school and had Cablevision at my residence, there would seemingly be a service outage on a weekly basis.