If we are talking about the lowest trading fee then here is some exchange with corresponding trading fee starting with the lowest. On the number one with 0.05% trading fee we have binance . At 0.15% we have poloniex, but there are major issues in poloniex and some lenders are waiting for some action during this month. The third was cryptopia with 0.2%, but as of now cryptopia is still undergoing some major issues so I don't really recommend using it. Lastly we have Bittrex at 0.25% trading fee.

I guess that leaves Binance and Bittrex since Cryptopia and Poloniex have some issues. But if you are afraid of the KYC data hacking which attacked binance previously then that would lead you to bittrex.