Depends on the Bass....
My main 2 are a '86 Jazz Bass Special thats (bog standard) black and gold hardware, and a '13 MIM P-Bass Black/black/maple that I changed the pickguard from white, and thats the sum total of mods for my "using" basses.
However.... I have a white PJ squire that I'm giving the Duff look, black tuners, black hi-mass bridge, black painted neck and headstock with pearl trapezoid inlays. I've put a tonerider pickup in the P slot but I'm dubious if its an improvement... Its been a bit of a project.
Also working on my Classic Vibe Jazz bass, its the 70s one black with the red tort, I'm going a bit stealthy on it, black pickguard, black covers and switches, not doing the tuners and bridge... yet...
Not done anything to my red sparkle Yam RBX thats a bit of a beater guitar, I tends to be the one I play/spill beer on/drop down the stairs at the weekend, but it keeps playing, and staying in tune and beeing generally amazing for a 90 buck fleabay buy.