Bittrex is still No.1 and for a very good reason it is the most secure crypto exchange around. Bittrex were caught a little with their pants down and were not ready for the huge influx of customers, which in turn leaves the site i. The state it is today, one that is laggy. But im sure this is beong worked on and it will be back to normal in no time.
Support a little slow. Relatively easy sign up & validation. Great choice of coins & very liquid. Simple ui with support for stop loss & take profit. Dedicated team providing ongoing review of coins security progress of development etc and removing those that fail criteria