Best ATM option for withdrawing cash (in China) is to use BOA Visa debit card, no fee from any ATM that belongs to China Construction Bank (widely available in most cities in China). If you don't have an account with BOA, you can open a basic no fee checking account (eBanking) then use online ACH at the BOA site to transfer in some money from Chase before you fly out to China. Keep in mind that there is a daily ATM withdrawal limit and the amount could vary, e.g., up to 2500 or 5000RMB/day in Shanghai.

Best credit card option is Discover card (processed via UnionPay in China) or other credit cards that have no foreign exchange fee (but do watch out for DCC as eluded by another poster).