If you goto a regular fiat currency exchange, there are some main contenders, USB, GBP, YEN and EUR - this is after a long time of the monetary system being introduced, the cryptoworld we live in moves so quickly that I feel there will be some main contenders in the not too distant future, maybe these are BTC, ETH, XMR, WAVES and some hotly developed Altcoins - what do you think should be on the list?