I've used both, but never had a problem with either. I had heard about the issues with Poloniex, and more recently Bittrex, but don't have any holdings on either of them right now. As thousands of new early adopters emerge month after month, I expect many exchanges will become more and more volatile as they become overwhelmed with the volume of new users and trading.
The Exodus wallet has limited trading built in for the cryptos it holds through shapeshift, that's always safer than holding them on an open exchange.