Like you said, ww was preceded by bad movies, so its standard is much lower. MCU sure gives CM a boost in its opening but also raises its bar so high. WW has some great moments but when it's bad, it's really bad. CM is a solid movie all the way through. Between the two, CM is the better one.
Also among the 5 days there's only one non-workday (due to May holiday rearrangment). Plus China's midnight preview scale can't compare to Thursday preview here. So China don't have much advantage.