I've done several sets of calipers for friends and family, with great results. I prefer the more subtle colors, but in some cases the brighter ones don't look bad.
In all cases I either removed the calipers or started with new ones. I also ground them smooth to get rid of all casting marks, etc. Even cheap Ford stock calipers look good when done well.
Again, my personal preference is to do them black or silver. It makes for a nice detail, that doesn't jump out at you. It's the way that they 'should' have come from the factory.
Honestly, if you were building a car from scratch, would you put anything on it that was just bare steel?