Not Bittrex, not Poloniex, Binance is best, reason is:
Most of the known coins are listed already on Binance.
Free GAS coin just holding NEO on exchange.
List most of the token post ICO.
Support all Bitcoin fork, and get free high valued coins just keeping Bitcoin in exchange.
User friendly layout design
Android and IOS App available for mobile trading which is too good, you can trade any time anywhere.
Monthly competition on trading
Use BNB (Binance coin) for fees and get 50% fees discount on every transition
Low fees on transition, compare to other big exchanges.
More then 2 Million users
Stop Limit functionality on trade.
any many more things...
Sign up if you are not already on Binance, once you sing-up you can download app and trade from mobile easily.
https://www.binance.com/?ref=10172828