Panasonic 50 gt50
panasonic 55 st50
I would go for the Paasonic 55ST50 based on its stellar and premium performance.
And it has the best black levels.
Home cinema system: Panasonic 50VT65 (THX calibrated), Pioneer Bdp-lx71, Pioneer Vsx-lx70, B&W FPM Series, B&W PV1.
Gadgets: iPad 2 and iPhone 4s. Headphones: B&O H6. Dab radio: Roberts Dreamtime.
Just bought 55HX853, VERY happy