We just redid our half bath and put in a grey vanity and the rest of the woodwork is white. For a main bath, I prefer either white or stained wood, but it would depend on the other finishes.
I painted a bathroom vanity navy blue, because it went with the floor tile at the time. It depends a lot on the specific room what I'd choose. I picked a greenish gray for our kitchen cabinets.
The first thing we found for our bathroom was the vanity, so the rest of our choices coordinated around that.
Since it sounds like your bathroom already exists, I think since what you already have in there that won’t be changing (tiles, countertop, floors, maybe walls?), the color of the vanity depends on those things.