poloniex all the way man. used it for a long time and will continue to use it.
poloniex is a good exchange with high volume in many coins with a lot of whales But still have some shit coins . also sometimes you need to trade alts coins that not yet listed in poloniex.
i do trade in these exchanges with order :
1-poloniex
2-bittrex
3-cex
4-yobit
Thanks