In my experience btc-e has been the most reliable and trustworthy exchange so far, they have an incredible daily volume, they have all the interest to keep it up and that's the guarantee that keeps it running.

It will be back online soon I'm sure, but if it doesn't, jeez, they have $50M in cryptocurrencies:
https://coinmarketcap.com/exchanges/btc-e/

I luckily don't have enough in btc-e. Good luck to anyone else.