Panasonic TH-58HX450 and Samsung HG55AT670UJ are well-equipped smart TVs that aim to provide a balance of picture quality, performance, and smart capabilities. There is a difference in screen size (58 Inch (147 cm) vs 55 Inch (139 cm)), and a larger screen generally provides a more immersive viewing experience. Both TVs offer adequate brightness levels suitable for most indoor lighting conditions. Both TVs come with smart platforms that support popular streaming apps and voice control features. Panasonic TH-58HX450 and Samsung HG55AT670UJ offer different motion rates (60 Hz vs 100 Hz), which can impact smoothness during fast-moving scenes like sports and gaming. Overall, both models are capable choices in their segment, offering a balance between performance, features, and usability. Both models support 4K 3840 x 2160 resolution, ensuring sharp picture quality with detailed visuals for movies, shows, and gaming. Both TVs provide standard built-in audio performance suitable for regular usage, though external speakers can enhance the experience.

Verdict: Both TVs are strong contenders, and your final choice should depend on your preference for screen size, motion performance, and smart features.