Both TVs offer adequate brightness levels suitable for most indoor lighting conditions. TCL 70S434 and Hisense 70H78G are well-equipped smart TVs that aim to provide a balance of picture quality, performance, and smart capabilities. TCL 70S434 and Hisense 70H78G offer different motion rates (120 Hz vs 60 Hz), which can impact smoothness during fast-moving scenes like sports and gaming. From a practical standpoint, both options provide a reliable viewing experience for most users. 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. TCL 70S434 and Hisense 70H78G differ in resolution (UDH vs 4K 3840 x 2160), which can affect overall clarity and sharpness of the display. 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.