Both TVs provide standard built-in audio performance suitable for regular usage, though external speakers can enhance the experience. Both TVs come with smart platforms that support popular streaming apps and voice control features. Intex LED-3900 features a 39 Inch (99 cm) screen while Sansui SJX40HB21CAF comes with 40 Inch (102 cm), which can make a noticeable difference depending on your room size and viewing distance. From a practical standpoint, both options provide a reliable viewing experience for most users. Intex LED-3900 and Sansui SJX40HB21CAF are well-equipped smart TVs that aim to provide a balance of picture quality, performance, and smart capabilities. Both TVs provide decent motion handling, making them suitable for everyday viewing including sports and action content. Both TVs offer adequate brightness levels suitable for most indoor lighting conditions. Intex LED-3900 and Sansui SJX40HB21CAF differ in resolution (1920 x 1080 vs 1366 x 768), which can affect overall clarity and sharpness of the display.

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