What is the best currency if the dollar collapses?

If the dollar were to collapse, what would be the best alternative currency to hold onto? Are there any stablecoins or cryptocurrencies that are designed to be resilient against such economic downturns? Are there any factors to consider when choosing a replacement currency, such as ease of access, adoption rate, or security? What role might gold or other precious metals play in such a scenario? And finally, is there any way to predict which currency might emerge as the most popular alternative in the event of a dollar collapse?