there is no magic answer, not every sunset is the same. if it were that easy, everyone would just go out with magic settings, magic formulae, etc, and come back with good pictures.
for CPL, one point i can mention is that for UWA coverage, you will get uneven polarisation. as such, i do not use CPL for my pictures, as most of my sunsets are taken with a UWA.
ND filters will be used when you feel that extending the exposure is beneficial. if you are at a field, versus being at the sea, it would make a difference, won't it?
GND filters will be used depending on situation. does the scene benefit from selective darkening of the top? if not, would exposure blending be better?
these are questions that you have to answer quickly when you face the situations. having strong technical knowledge will allow you to answer this quickly and decisively when you are there, and pick and choose the tools from the toolbox available to you and use them to get what you want.
once again, there is no magic bullet or one size fits all solution.
If sunset or sunrise, I presume you will want to include that in the frame, making CPL quite useless anyway, since CPL works well perpendicular to the sun.
If my shot includes water, and I want to smooth the waters out, I will want a longer exposure. I may opt to go for a ND.
If the difference in exposure between the bring areas and dark areas are too great, i will use GND to balance them out. But that is not the only way to do it. You can bracket the shots with different exposures and blend them using layers. Or you can use HDR. Or you can use ND to extend the exposure, and opt to use the black card technique.