I trade only on a few exchanges and my primary thing which I look for is security how secure is the exchange. Secondly, I look for liquidity how much daily volume is that exchange having. Thirdly I look for how frequently they list new potential coins to their exchange.
When an exchange do have big volume then it would always correlates that it do indicates that this is a good exchange. Security do always matter
and a must have thing to consider for those owners of such exchange but the thing we should put up on our mind that even how safe or secure the exchange was
never ever store up big amounts.