Generally plasma has better blacks/contrast and LCD may get the edge for color "pop". Plasma is better for off-angle. LCD is much better in a sunny room. Really is that simple.
For me, plasma wins hands down for PQ. Panny in currently the best (I am NOT a big fan of Samsung quality - 3 failures in the family in with < 3 year old Sammys).
A hint. Take a look at Panny's "Professional" monitors. No tuner and no speakers - less expensive. If you are hooking up to a cable or Sat box and a receiver/5.1 setup, you don't need (or need to pat for) a tuner/speakers in the TV. Plus, the Professional models tens to have more adjustments/controls for calibration.
The Visual Apex website provides a list of the Professional monitor model numbers and you can Google the prices online.
Whatever you decide to get, the TV will come set to "nuclear torch" mode. Get on the internet and search for settings people have done for the model number. You will want to change from "Vivid" (or whatever they use to describe sunburn mode) to something a bit less drastic.
Good luck.
