Memories of people freaking out about their money stuck on Bitfinex for weeks without any feedback from the exchange are still strong. Just like Polo giving us a recent and still present Mt Gox scare. Bittrex is the only way to go for me for now. Only possible motive for going to Bitfinex would be to trade EOS, but it will be tradable all around soon enough.
There's no guarantee that Bittrex (or other centralized exchange) will act better when being hacked, but at least Bitfinex solved the issue and covered the losses. It is constantly improving (you can notice some new features almost every week) and the support responds in just few hours (which is rare for most of exchanges).