I just bought the samsung hp s-5053 and it is amazing. I compared plasma tv's for three months. I looked at pioneer(non elite) and panasonic models but kept coming back to the sammy. It definitely has a better picture than the other choices with dvd's and high definition. I hear people comparing sets in stores without checking the type of input and it drives me crazy. If you don't hook up a tv with at least component it is not HD. Also, you never know how many times the signal has been split before it goes to the set you are viewing, even if they are right enxt to eachother. Although I preferred to buy at set from Costco for their great warranty, i decided to buy the better set from Sears without it.
I can't comment on SD comparisons but SD looks fine to me on this set. I have it hooked up to a moxi and xbox 360 with component, laptop via vga(love the auto adjust feature for this. Fills the screen and looks perfect) and Oppo 950 va HDMI. I have it on warm2 and movie mode which looks the most realistic to me and supposedly closer to 6500K. I also used avia for calibration but prefer the movie mode. Go figure.
Any way, IMHO I like it better than your other choices for connections, picture and looks.