First of all I would say it all depends on the price.
In the premium price range my personal favourite is Pioneer and their latest KURO Plasmas (
Pioneer-PDP-428XD or
Pioneer PDP508XD FreakScore 8,3
Stepping down at almost half the price Panasonic offers a extremly popular 42" plasma,
Panasonic TH-42PX75U with a FreakScore of 8,6
Both are excellent choices in my opinion.