If you're trading internationally, and have to denominate on a given currency, would you use the one backed by China, or the one backed by the US? Would you use

If you're trading internationally, and have to denominate on a given currency, would you use the one backed by China, or the one backed by the US? Would you use a new currency with nothing yet denominated in it, or the one in which trillions of assets are denominated into? The one backed by a legal system that in the end is a reflection of the whims of a single ruling, communist party with an inaccessible and arbitrary hierarchy, or the one backed by the, yes, imperfect, but still pretty much free and open legal system? It's never about the actual money. Or the technical aspect of it. It's about trust.