I used to like Poloniex because the site was designed nicely. Ever since they started holding my steem I've hated it. I've also lost some steem using it.

Recently, I switched over to Bittrex and felt like I actually had freedom with my crypto assets. Bittrex is simple to use and doesn't hold my cryptocurrencies like Poloniex did. I have also heard about Poloniex planning an exit scam. Be Careful, Do your research.