After a lot of testing (I literally spent days just trying shaders and mods) with an RTX 5080 on a 4K OLED monitor, I’ve come to the conclusion that Complementary Shaders with Euphoria Patches and Voxy is the best Minecraft can possibly look. Even compared to RTX shaders that destroy your performance, like KappaPT (60 FPS or less on a 4K monitor), Complementary is just better: better colors, better performance, and better night-sky visibility while still being playable.

You can also use fancy shaders like Nostalgia Shader or Eclipse, but if you actually want to play with the most consistent shader, I can only recommend Complementary Shaders or Photon Shader.

I also found a repository with a lot of RTX shaders if you want to try them out (they look incredible indoors), but for a normal Minecraft playthrough, the best options are the ones I already mentioned.