To start off, here's a nice guide for you to get an idea of what you'll be getting, should you decide between one of the two: Plasma vs. LCD
Okay, now for my answer: It depends. LOL. Really it does. My uncle has a nice 60 inch Plasma, and my wife's grandpa has a 40 something inch LCD. Both TV's look great, but to be honest over all picture quality looks better on the Plasma. He's had it 6 years now and the picture still looks amasing in HD.
The Plasma you listed as a Dynamic contrast ratio of 1,000,000:1
, while the sony has a dyamic contrast ratio of a mere 16,000:1
and the Samsung has a dynamic contrast ration of 50,000:1
Put simply, contrast ratio is the ability of the TV to display deep blacks without loss of details in shadow or dark scenes. For example, 1,000:1 means the white is 1,000 times brighter than the black.
Go with Plasma if you really plan just movies and TV, however if you ever plan to use as a monitor, you are best to get the Samsung.