I don’t prefer bullion per se but rather junk silver. Silver American coins that are recognized as money and are in convenient proportional units.
Don’t know what will be the most negotiable form of silver, but it looks to be the most practical metal for a medium of exchange when (not if) we have a currency collapse.
Now, if we end up in a state of anarchy, who knows? Food stuffs and water could be the medium of exchange. Can’t do everything with barter.
Anyway, it will be something besides paper money, you can bet on that.