52a650 is what im picking up next year
the 750 is paying more for extra bells and whistles you wont use imo. some people do but i wont ever.
the 850 is thinner but only really not that great

120hz is dope imo...considering i work and see all these tv's everyday i actually think that the 120hz is something you need if you watch blu-ray or hd
the touch of color red is nice. i like blue better, but everyday the red is better imo