LED is just a form of LCD.
TV Size
TV size matters first and foremost.
- At 37" or smaller CCFL LCD is all you need (and really all that's out there)
- At 40" - 47" its a bit of a grey area. Some argue for going to LED or Plasma, but others feel you can still get top notch HD viewing in CCFL LCD. In these sizes you really need to go look for yourself.
- At 50"+, most consumer and nerd HDTV guides will recommend you move into LED or Plasma offerings; because at those sizes you'll be more likely to discern the quality/detail advantages those technologies offer
LCD
LCDs inherently suffer problems with motion playback. They suffer from motion blur (ghost trails). This is compensated for with the 120Hz/240Hz refresh rates. This feature helps out a lot, but is not 100%. And you are expected to pay a price premium for this add-on.
CCFL LCDs in larger sets are sometimes accused of having muted colors, grey blacks, and so-so contrast. This is compensated for with the modern LED LCD. The LED backlight provides a massive jump in quality in regard to those 3 things. It brings it to a near Plasma/CRT/DLP level. But, besides 3D, this is the most premium feature in LCD's and comes with a heavy price premium (but does deliver good quality).
Plasma
Plasmas are inherently near instantaneous in their refresh rate with 0.001 ms response time. They are flawless in motion playback. Because its inherent to the technology, you pay nothing extra for this "feature."
Plasmas inherently deliver vivid color, true blacks, and deep contrast. They do this right out of the box. They are a better overall image. And so you get a better image and perfect motion playback without having to pay anything extra.
Plasmas only currently suffer from many myths and misconceptions. The main ones being that they suffer from burn-in, they are more expensive, they have shorter life spans, and they are energy hogs.
Modern Plasmas do not suffer from burn-in. After they are conditioned, you would have to actually work hard to accomplish a burn-in. To condition a new set all you need to do is keep the brightness and contrast turned way down for the first 100-200 hours of use. After that optimize and enjoy.
Plasmas are not more expensive than LCD rivals anymore. Any especially with LCDs needing high end features like 120Hz and LED backlights to compete. Those features often make LCD far more expensive to buy.
Plasmas do not have shorter life spans. The reputable brands will deliver models that are rated to 60,000 - 100,000 hours. That basically means that in 10 years time, at 8 hours a day, 365 days a year, you would only really see at most about a 10% loss in brightness. So the set is likely well useable for beyond 10 years.
Current Plasma models are now energy star certified. This means no more being power hogs against LCDs. They can match LCDs in this regard. But every model is different. There are some LCDs that still perform better, and there are some LCDs that perform much worse. It changes ever year as new models come out.