Best platform for exchanging for now is Poloniex , Bittrex with Margin lend but i suggest you not to use that option if you're really not an expert in trading, cause it can hurt your capital really much if you're not success. The next one is liqui.io with variety potiental coins that maybe can make you be consider for a long time. Last one i want to introduce to you is kraken with the outstanding option is the autobuy one which can make you earn really good profit.