I've tried a lot of shaders, and for free shaders, Sildurs is definitely the best in terms of just looking good. SEUS is way too harshly realistic imo, everything looks too bright or too dark most of the time. Sildurs is colorful and looks very good. Continuum is also worth a try, it's sort of a mix between Sildurs and SEUS
For shaders that cost money, the latest versions of SEUS is probably the best but only because of the ray tracing capabilities.
