50 Samsung Plasma is what we bought about a year ago. Awesome picture, the Olympics were breath taking.
Plasma is better for offset viewing, it can be seen at any angle, so consider how your living room is set up. Bad thing is they have thick glass screens and have a lot of glare, so if you have a bunch of windows, it can be annoying. Plasma is not very eco-friendly, the stuff it is made of really should be recycled and not just trashed. Conscientious disposal could be an issue. Plasma will suffer burn-in on the picture. If you play a lot of video games, some of those images can get "etched" into the screen. It can be erased or will fade with time. We play the Wii occasionally and have had no problems, but some of the banners on ESPN will burn in once in a while. I ignore it and it goes away in a short while.
Plasma is cheaper, much cheaper than a comparable LED TV. If you are planning on watching a lot of sports, you need to pay attention to the mhz of the TV. The higher the better, it has to do with the screen refresh rate. I don't know too much more about it, but I am sure somebody here does!
Good luck, it's a hard decision. Might want to subscribe to Consumer Reports for a month online and do some quick research, they have a lot of info. They are a great resource for these types of things.