People argue the topic of image quality WAY too much. If purchase any of the top-tier brands -- Pansonic, Sharp, Sony, etc., you are going to get a great picture IF YOU CALIBRATE IT PROPERLY. Even if you downgrade and get something like a Magnavox, Vizio, Sanyo, Westinghouse, or some other "cheap" brand, once calibrated properly it will still look "good". Yes, there are some that just look like rubbish, but my neighbor has a 47" Polaroid and it works great and looks great once all the colors and hues are set up properly. Quit worrying so much about one set having 5% better contrast and get a decent brand TV with the FEATURES you want. I.e. Inputs, Native Resolution, etc.
As far as Plasma Vs. LCD. Plasma DOES have some degree of burn in that has largely been overcome through different technologies in the hardware. LCD "lag" times aren't that bad any more. My Sharp Aquos has a 4MS response time and I haven't noticed any trails, sharpness, ghosting, blur, or anything else when watching HD Football. I game a lot and went through this same decision process and decided burn-in wasn't worth the risk. I shopped and shopped and finally bought a 42" LG 1080P that was a "super sale" at $999. Sears sold too many and couldn't deliver so I forced their hand and they substituted a Sharp Aquos. Point is, be patient and watch for a deal and don't get in a hurry. Slickdeals is a good place to watch.
I hate trolls.

Systems I currently own: 360, PS3, Wii, DS Lite (2)
Systems I've owned: PS2, PS1, Dreamcast, Saturn, 3DO, Genesis, Gamecube, N64, SNES, NES, GBA, GB, C64, Amiga, Atari 2600 and 5200, Sega Game Gear, Vectrex, Intellivision, Pong. Yes, Pong.