Suppose you have hard water and can get scale buildup. Which surface is least likely to get scale buildup? And if you do get scale, from which is it most easily removed?

[I also wonder how black powder would fare in that regard, though that's just my curiosity, since that color wouldn't work in my current bathroom.]

And are there different qualities of chrome, brushed nickel, and brush stainless surfaces?

E.g., would the chrome finish on a Moen faucet be more durable, and more resistant to scale, than that on a Home Depot Glacier Bay faucet? Or do they all pretty much use the same deposition material and process, such that to the extent those faucets differ, it's not in the durability of the finish. [According to Moen, their finishes are the same on all their faucets, so at least within that brand there should be no differences.]