to the OP:
I think what you need to do is go into a store such as John Lewis / Currys and look at the comparison wall. It will physically show you what the difference in picture quality is like. All 3 technologies (Plasma, LCD , LED) have their advantages and disadvantages. See what suits you, read up on it and make a decision.
If i were you and wanted a plasma, Id definitely get Panasonic, if Pioneer were still in the market, it will be a pioneer.
I myself have a Samsung LED and an LG LED, cant tell a lot of difference in terms of picture quality, samsung maybe has a bit more vibrant colours, and the LG has slightly better motion. I use the Samsung in my bedroom more though because it plays most major formats of my movies from my server.