If you are going to watch it in a bright room with alot of windows or lights, then definitely go with an LCD because of less glare and reflections. I feel plasma's give a better picture and tend to have better STD def pictures as well. They are better for fast motion too. To me the pictures look more natural but its a close call.

I just bought a 52" Sony LCD XBR4 and wish I could have gone the plasma route (sorry Pix!). But my TV faces 4 huge windows.