So what's the best coin to buy a cup of Coffee with? Transaction cost must not be expensive and the transaction must complete before the Coffee gets cold... 
Better paper money has not yet come up with anything, we must first look for a café that accepts payment in the crypto, and then think about how to pay. Do not try to pay with cryptocurrencies in China or Vietnam. In these 2 countries, cryptocurrencies are not accepted by the government for payment, you will be in trouble if you try to use cryptocurrency as a currency in these countries.