I am a Bittrex user and I will be honest, I like it. It is not the fastest platform but they have a very good range of altcoins if you like trading and they have a good orderbook if you want to sell btc fast. The only issue is their verification which is difficult to complete,,, but I guess not more difficult than other platforms.
Stay away from their IEOs;)
People are getting use to this verification thing now, because virtually all exchanges and all projects platform do request for KYC, I have heard lots of great things about bittrex also and I think it will be the second choice of people to Binance, I have never used tem really to know if their verification procedure is same as that of Binance.
For Binance, they have verification requirement too, but theirs is a bit flexible, it becomes very necessary for those who are trading above certain amount of money and that is like grade 11 user, I think for the low level user, there KYC stuff is not Much mandatory for them. Anyway, I hope that one day, I will see reason to use bittrex, maybe they will have a coin I am interested in that is not on Binance, but for now, all the coins I wishes to trade are onBinance.