To be honest, I would stay as far away from Bithumb as possible. Too many security breaches (at least two successful hacks) and more than USD$31 Million stolen by hackers (that's the disclosed number; who knows how much hackers had stolen in 2017). That's not an ideal platform to put your money on to, in my humble opinion.

I would add Bittrex as well—trading for two years on that exchange, and never had an issue, it is one of the top.