My favorite is Bittrex, mainly because there panic dives on BTC and ETH usually go lower than many other exchanges, yet they are very liquid.. Kraken is the safest exchange in my opinion, and works with Fiat (usd) instead of tether (usdt) which is getting some bad rumors lately of legal troubles.. Hitbtc uses Fiat also, but i constantly have issues with there platform freezing up.. Poloniex is another big one, but they have had issues lately, entire site going down and I have moved all my money out, while they resolve out there issues. Cryptopia and Liqui are pretty small, and most of there coins have thin books..