aren't LED TVs just LCD with a different lighting system? (they are lit with leds rather than strip lights.) Which means they still have light passing through the pixel. So to make black, the light is blocked rather than off. in a plasma system the gas isn't stimulated so black is void of light, therefore blacker.
I was only suggesting plasma screens for colour, nothing else

I actually don't have a TV.

btw,
CRTs are still the best for colour, but i'm talking about grade one monitors. They will still be used in post production until an alternative is found.