If your room has lots of windows for sunlight, the sony has a non reflective screen. I have both a 52" 650 sammy and a 2 year old 40" sony d3000 with the 10 bit panel and 120hz motionflow, and they both have their perks. I find that the motionflow on the Sony is more natural and 3d looking, whereas the AMP on the samsung is clearer and makes things look like they are right in front of you. Personally, i like the sony method better.
Also, the colors on the samsungs are great because of the reflective screen.... they make the colors pop, and look incredible. the sony TVs are more sharp looking and the samsungs have really great and powerful color. The Z series definately has better color than my D3000, but it's not as good as the sammys IMO
personally, i'll prob upgrade my 40" bedroom sony to the 52" sammy next year and i hope to replace it with a sony 52" with 240hz motionflow or dimmable leds for the living room. But either choice is a fantastic TV and i often don't know which one i'd like to watch TV on.