I voted no preference.
I have a couple of gold coins on my wish list (a Florentine florin dateable to a year I don't already have, and a Charles V type), but I have far more silver. There''s just more variety.
I would never vote iron or zinc, but I have parted with some gorgeous aluminum coins because they no longer fit my themes.
Whatever the heck Florentine bronze is, I doubt it belongs on a list of "compositions."