But I believe that still Binance better Bittrex due to the fact that on BNB, if we assume you have a NEO you comes GAS and TREX all takes in their hands.
As the number of users exceeded 5 million. What makes this exchange one of the most liquid for trading
Binance was my first exchange and I still use it the most. It did slow down a couple of weeks ago I think because it couldn't handle the sheer number of trades but I think they are working on improving that now.
Kucoin is interesting as it's format is very similar to Binance except that they offer some more unusual coins with a lower marketcap (see my signature at the bottom of this post for my ref link to Kucoin). Both of them complement each other quite nicely.
I'm always open to trying more exhanges so recommend one if you think it can compete with Binance or Kucoin.