Poloniex is the first exchange where i have bought crypto currencies from other currencies. It has a easy to use interface which gives user a better comfort zone. Margin Trading and Lending is one of the useful feature which i have noticed in poloniex. Trading fee on poloniex is not much higher as compare to other. As it is based on USA, exchange is more secure and reliable. Once its iOS version is available it will be more useful than any other exchange.See full review