Just spent 3 months doing the research on this shit before buying mine.
1. Plasma has better color accuracy
2. Plasma has much better off-axis viewing.
3. Plasma has faster response time (i.e., nanoseconds vs. milliseconds for LCD/LED)
4. Plasma is usually cheaper, inch-for-inch, feature for feature.
5. LCD is available below 40" (plasma is not)
6. LCD/LED is better in extremely bright viewing environments, i.e., if your living room has lots of windows full of sun and you can't block it very well with curtains, blinds, etc.
7. LCD/LED sells better because people notice the brighter picture better in insanely-bright showrooms at the big box stores... which are nothing like your home viewing environment, most likely.
8. Plasma has better absolute black levels (yes, even than LEDs... it's a limitation of the technology used in LCDs/LEDs)
9. Plasma has better native contrast ratio (note - as mentioned above, dynamic contrast ratio means exactly shit - they CANNOT display blacks and whites at that contrast ratio side-by-side simultaneously, thus making them useless specs.
10. LCD/LED are lighter, on avg about 10-15%, more when buying the extremely high-end LEDs.
Those are some of the things I learned in all my research. Some of them mattered to me, some of them didn't. It all depends on your particular application.
And as for the whole "burn-in" issue with plasmas, it's not a thing of the past, but with some common sense and new technology, it is much much MUCH better than it used to be. It's also very brand-dependent. Cheaper lower-quality manufacturers have higher burn-in problems and higher failure rates.
Also look at customer service ratings.... Samsung has one of the worst reputations in that regard. //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif