Sildur’s is the king of compatibility. If you are running 200+ mods and want shaders, use Sildur’s. It rarely breaks modded entity rendering and looks lively.

projects which aim to backport modern optimizations to 1.12.2. Recommendation VintageFix CensoredASM

Continuum is not just a shader; it is a tech demo. If you see a photo of Minecraft on Reddit that looks photorealistic, it’s probably Continuum.

To improve Minecraft's visuals with shaders in version 1.12.2, you'll need to choose and install a shader pack. There are several popular shader packs that work with Minecraft 1.12.2, including: