Picture quality

There's no meaningful difference between the GT50 and the ST50's picture after both are properly calibrated. Both are outstanding performers, among the best plasma TVs I've ever tested, and just shy of the picture afforded by the much-less affordable TC-PVT50 series. Samsung's PNE6500 and PNE8000 scored the same as ST50 and the GT50 in this category, but I'd pick the Panasonics because of their slightly better light output (at least compared to the 60-inch Samsungs).

I mentioned calibration because that's how I compare all TVs--only after adjusting their picture settings to the best of my ability (and since I publish my settings, readers can get their own TVs very close to what I see and compare in the review). But you might be wondering whether the GT50 can beat the ST50 before both are properly calibrated, since the GT50 has the THX modes and the ST50 does not. Comparing the GT50's best THX mode to the ST50's best mode, Cinema, I found that THX Cinema was slightly superior in grayscale and gamma, but dimmer and thus less punchy overall. Of course you can increase the liht output of THX Cinema on the 55-inch GT50, eliminating that difference, but even after that THX on the GT50 isn't that much better than Cinema on the ST50--certainly not worth the price difference alone.

Read the full review of the Panasonic TC-PGT50 series