Bitcoin, because Bitcoin is the most expensive currency in the world. Whether it is its history or its value is always the highest.
For sure bitcoin is the most valuable currency and it has very good value and price, no currency can be like bitcoin because it has very huge potential and stamina to increase in price, growing price of bitcoin makes it high in value, bitcoin was invented firstly so bitcoin is the mother of all other crypto currencies, if we look at the growth of bitcoin we will see no currency has been that reliable to use ever in past, price has become more than triple from the beginning till now.
