I like the CNET site for reviews.
Panasonic has a good name in Plasmas but not all their models are equal. Sometimes a Samsung plasma 650 or 550 might be better value for the same price or less.
For LCDs the Samsung 650 gets lots of raves for value and performance. The 52" asking price at best Buy is $3000 though. Try bargaining and look around for a deal. Here's a price of $2600 so if you can price match for another 10% off that would make it $2340. Also new models are coming out so the old models may be marked down.
http://www.gibbysaudiovideo.com/sams...tv-p-2611.html
If you want to go very top end in LCDs look for the Samsung 950 with the LED backlight. Other manufacturers are also coming out with LED back lights.
Here's the CNET TV review site.
http://reviews.cnet.com/televisions/