Don’t use poloniex! My Withdraw from them is stuck since last week. It has been days and still haven't got a single word from their support in ticket that I submitted. A lot people have problems with withdraws and with deposits not reflecting on their accounts.
Also, some coins just got disabled for several days – while wallets of that coins was not empty. Poloniex wont allow any exchange/withdraw or fill them – only can see the balance.