Plasmas are generally seen as the better ones to go for, in terms of colour and the like.
However, the connection feed to the set is quite important, always go for HDMI ports if you can or the next highest after that. I had played at a friend's set on COD with SCART (on a 42' Plasma)...previous to that, was playing at another friend's LCD with HDMI. OH MY GOD, the Plasma SCART looked quite bad while the LCD HDMI looked clean and crisp.
So, basically if you get either you will not get HD gaming (or films) unless you use HD connectors.
The family both have 42' Plasmas from Panasonics and they're really are quite good quality. They just need to be tuned in slightly more to totally bring out the colour, but as the rooms they are in have variable lighting due to different perferances for television watching from different people....they'll need to be left alone.
Salespeople....Never listen to them if you have done your research on what you want to get. They're there to cater to your wishes, not them to bend you to their wishes. Unless of course, money is of no cost to you.