This is likely a question that you will not solve definitively as, in my opinion, it's a matter of personal preference. This being the case, your ears and brain will often mislead you.
My personal preference has always been for brass, with both saddles and bridge. My preference for nut material is natural bone, and seasonally shed elk antler is what I've used for several builds and change outs on both fretted and fretless basses.
I stopped chasing tone about 10 years ago when I was able to use this combination as I wished, and changed my amplification rig to Bergantino. I have achieved the tone that has always been in my head.
Was my personal tone perfection the result of brass and antler? I'd sure like to think so, but the real answer is, probably no. After all, your ears and brain conspire to fool you. Even knowing about about this vile conspiracy, I'm happy. The fun is in the journey.
And a final discovery: as a player becomes more proficient with the instrument, and technique improves, a greater sense of personal style becomes evident. When this level is reached, tone magically improves. Coincidental? Don't think so.
Experience: I started playing both guitar and bass in 1963 and have focused most of my efforts on bass since around 2000. Although my "money career" was not in music, I've enjoyed active and rewarding stage time. I retired from the stage in 2020, but I'm still wood shedding most days.
Best of luck with your journey.
Koog