120hz refresh rate is a MUST. Be careful at WalMart/Best Buy/Sam's Club. Especially wal mart sells cheap tvs cheaply. Look at consumer reports, but most major brands are okay (LG, Panasonic, Samsung). Westinghouse is garbage.
Plasma better if the room has lots of natural light (better blacks), LCD is fine if there isn't a lot of light to reflect off the screen.
go led-lcd if you're getting an lcd tv, don't cut corners.
plasma actually is still the best in regards to picture (most life-like) and abilty to process motion. but the drawback is how long it will last and there being no real recourse for it other than buying a new tv.
get a good led and you won't regret it. i recommend the samsung smart tvs.