Chrome and nickel (plated) are options if you want to match hardware that’s on the guitar. If you won’t see the screws or don’t care about appearance, stainless has no chance of a plating wearing off from screwdriver contact (most durable). Chrome is best for corrosion protection, but often nickel is used in bridges and pickup covers for tone, so there’s hardware to match everything.

You know I haven’t built a kit yet - I generally try not to give advice where I don’t have experience. But my background is in aerospace and marine engineering and I do have plenty of experience designing hardware and components from nickel, steel, and corrosion resistant alloys.