I'd say OLED > LED LCD > LCD > Plasma
But OLEDs are fairly new and I don think you can get a 50' yet
http://www.sonystyle.com/webapp/wcs...oductId=8198552921665327724#additionalImage1"
An 11" Sony XEL-1 OLED TV will run you about 2 grands (when its out).
The XEL-2 is Sony's 21" OLED TV in the work thats supposed to have "Full HD", but I have no clue what the price of that will be, probably twice that of the 11"
Other than being yet even brighter with lower power consumption, the biggest benefit of OLED is being lighter and actually flexible (the two TVs above are supposed to be super thin).