Most reserves globally are being held in Euro (>55%). It's just that USD is common through the Internet as the Euro have been around only for the last 5 years. So USD is the most popular currency on the Internet. For me personally is good to buy products and services in USD, but I hate it when I have to exchange to Euro (I am from Greece). Some years ago the rates were 1:1 or even 0,85$ to 1 euro. Today it is 1,35$ to 1 EUR. There is always going to be benefits and losses no matter what kind of currency we use. Depends on whether you are the buyer or the seller. Damn!!! I have to start buying in USD and sell in EUR...