Used to be a Bittrex fan because of the number of trading pairs and liquidity, but they're too unpredictable. Removed a few of my coins and caused them to dive in price. I'm now a Kucoin, Binance and Huobi convert. Plenty of choice over the three platforms. Plus I like Cobinhood too, still early days, so liquidity not great, but can see it being a big player soon(ish).