My Job is selling tvs for a living:
1)Sony is the best, but you must get the right one. The V series and below are junk. The W and Z series are great. All XBR's are the best LCD's on the market
http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&langId=-1&categoryId=8198552921644628896&N=42949556672)Samsung would be second to Sony. DO NOT buy one of the LED Samsungs as they are only side lit LED's. Therefore the LED's must be too bright to light the whole TV. The effect is everything looks Fluorescent. Instead spend less $$ and buy a series 700 LCD
http://www.samsung.com/ca/consumer/detail/detail.do?group=tv&type=tv&subtype=lcd&model_cd=LN52B750U1FXZA3)LG would be third. Best looking LED's on the market(thinnest) and they are not side lit, they are fully back lit therefore not as bright and unrealistic(Samsungs LED). The reason they are cheaper than others is that they manufacture EVERYTHING that goes into the TV. From the paint to the panels to the processing chip. All the other companies buy supplies from the other manufactures(Sony buys all the panels from Samsung). When they manufacture everything they eliminate the middle man, therefore having lower productions costs. But because they manufacture everything they don't have top of the line everything.
http://www.lge.com/us/sl80/index.jsp4) Sharp would be forth. They have fallen a lot. Very average TVs
5) Toshiba- Best for gaming. Average for everything else
6) Vizio, just plain suck
With every LCD manufacturer they come standard with a 60 hertz speed. The higher end models have 120 HZ. The highest end models come with 240 HZ. DONT buy a 60 HZ TV as they all look like shit. If you can afford it get a 240 HZ(best for high motion Example: sports action movies). If the TV you are looking at doesnt tell you the HZ, that means it is a 60 HZ. Again make sure you get at least 120 HZ.
Pioneer had the best PLASMA TV on the market with the KURO technology, but unfortunately couldn't afford to keep making TV's(fucking recession). They sold all of their KURO technology to Panasonic. A Panasonic Z series TV is basically a Pioneer.
Hope that help
Last get 1080P instead of 720P, the cost differential is worth the extra pixels.