Least favorites:
-Dark wood natural finishes
-Purple. Just...don't
-Black (boooooring)
-Green. Seafoam, surf and Sherwood are cool, but anything really green is just ugly.
-Relic'd or Roadworn. Just stop trying, get a new bass, and put the mileage on it.
-Neon anything (unless you're in like a hair metal tribute band)
-Any fender with a black pickguard. I cannot express how much I despise Fenders of any color with a black pickguard (especially sunburst)
-Sunburst with a White pickguard, it just screams cheap 90s to me for some reason.
-Jetglo Rics
-Butterscotch. You know that horrendous Butterscotch they put on the Standard P's in the early 2000s with the black pickguards? Yeah, barf.
Conversely, I love pastel 60s colors, especially Fiesta red, adore Paisley, think Antigua is pretty cool, and I like Sunbursts because I think they wear out the best. I also like light natural finishes. Exotic wood is cool, and on Fender's natural reminds me of stripped finishes in the late 60s/70s, which I think look cool.