My base currencies used to be the Etherum and the Bitcoin at my first trades on exchanges but today it has totally changed. Because of the high withdrawal fees i wouldn't trade with them. If there is a chance i would like to use the Stellar or Ripple or Dogecoin. Those three coins withdraw fees to low just like 1 piece each, if you check the withdraw fees around 0.001 for BTC and 0.01 for the ETH. So when i use XLM i only pay 0.00001851 BTC.