Discussion Title: What is the best backing for currencies?

1. What is the best backing \(includes pegging\) for currencies?
1.1. Other currencies
1.1.1. Pro: Cryptocurrencies
1.1.1.1. Pro: These are sustainable
1.1.2. Pro: The dollar
1.1.2.1. Pro: It's used by most of the world.
1.2. Gold
1.2.1. Con: The world got off the Gold Standard due to the [issues](https://seekingalpha.com/article/4048750-problem-gold-backed-currencies) with it.
1.3. Economic units
1.3.1. Pro: Assets
1.3.2. Pro: GDP
1.4. Oil
1.4.1. Con: It's unsustainable