I looked heavily into tv's a couple of years ago when I was looking to buy my HD bigscreen. Here's the info I learned, but keep in mind, this was a couple of years ago.
CRT is still the best quality picture out there. But as mentioned previously, if your looking for a big screen, you won't find it here. And they're REALLY Heavy.
Plasma's have an Excellent picture, but they suffer from burn in, which is Very possilble playing video games, or watching ESPN and stuff. Plus, The shelf life was only like 5 to 6 years before plasma cells started burning out, and there's no way to fix them. Plasma's are also flat and light enough to hang on a wall.
LCD's are also flat and light enough to hang on a wall as well. But you want to make sure your sitting a good distance back from them, or else you might experience the "screen door effect". Where you can actually see every pixel on the screen. Again, this is only if your sitting close to the TV.
Let's not forget about DLP's now. That's what I ended up getting for myself a couple of years ago. Although they are light, they're not flat enough to hang on a wall. I think my 61" is only 12" deep though. They have a brighter picture than LCD with better black levels as well. The downfall with them, is that they perform at their best in a dark room. In a well light room, the picture just doesn't appear as bright. One other small thing to keep in mind is that a VERY small percentage of people experience the "rainbow effect" from DLP's. You can determine if your one of these people by looking at a tv in a department store.
Well, there's some things to keep in mind. Overall alot depends on you. How you'll use it, where you'll use, what size you want, what you want to pay. Best advice is just go to the store and decide what's best for you by looking at all of the TV's. Just keep in mind, most of the time in the department stores, the TV's settings arn't properly adjusted as they should be. Good luck in finding your tv.