I was told, and I dont claim this to be true, but this is the what the best buy dude told me when I was shopping around.
LCD, has longest life IIRC, but the slow refresh rates can leave ghosts or shadows in the screen. So for action tv, such as sports and such, not a good choice. I have noticed with my cousins LCD a little ghosting from time to time watching football.
Plasma, has the brightest picture. But because of the glass fronts, often has bad glares. If you are putting it in a basement or a place with no windows, the guy recommend this.
DLP, the main downfall was having to replace the bulbs.
I dont guarantee this info is correct, just throwing in what I was told, by someone who potentially has more knowledge than me in this. I ended up choosing DLP, mainly for the price, and I really have nothing bad to say about. Picked up a 46" Samsung for under 1400 I believe. Im no TV pro, but I personally think the picture quality is great. Maybe not the best, but for the price I think it was very nice.