Overall, both models are capable choices in their segment, offering a balance between performance, features, and usability. Panasonic TH-43MX660DX and Samsung 43U8400HLXL differ in resolution (4K vs 4K 3840 x 2160), which can affect overall clarity and sharpness of the display. Both TVs offer adequate brightness levels suitable for most indoor lighting conditions. Both TVs provide decent motion handling, making them suitable for everyday viewing including sports and action content. Both TVs provide standard built-in audio performance suitable for regular usage, though external speakers can enhance the experience. If you're comparing Panasonic TH-43MX660DX and Samsung 43U8400HLXL, both models come with modern features and are designed to deliver a solid viewing experience across different use cases. Both TVs come in similar screen sizes, making them suitable for comparable viewing setups and room environments. Both TVs come with smart platforms that support popular streaming apps and voice control features.

Verdict: Choosing between Panasonic TH-43MX660DX and Samsung 43U8400HLXL depends on your usage, whether you prioritize display quality, smoother motion, or smart features.