Also it's down to personal preference, hell I know some people who think that tape sounds better than CD and someone that thinks their clapped out old car feels better than my nice comfy new-ish one.
Thankfully not everyone thinks the same in this world
Personally, I've not noticed a BIG difference in the quality between ntl and Sky but then I've never had ntl through anything other than my computer TV card which claims to do stereo and a set of Creative labs 4.1 speakers.