Yep do your homework- Plasma's use a LOT more power to run- so higher electric bill. LED's are better in regards to something going wrong in there than the LCD's. LCD's and LED's have backlighting. LCD's use fluorescent backlighting, whereas modern ones- LED's (light emitting diodes) to light up the display. It really comes down to LED backlighting vs the fluorescent.
LED's have better contrast. LED's consume less power than LCD's. LED's can be viewed from more of an angle more clearly and are supposed to have better color.
One advantage is if the lights in the LED dim any at all, you will probably not even notice vs. the fluorescent tv, in which you may get 'dark areas' in your picture.