3. Michigan may own a bit more reputation in China than Georgetown does, but never much - it can never be on par with H/S/W or even Yale, Berkeley and UCLA in terms of brand name recognition.
Have you ever considered visa issue? You can find that three guys got offers from MIT but could not get visa last year. I also have similar painful experience.
My suggestion is that before you get F1 visa, do not say goodbye to Oxford.
One of major reason doing MBA is to be part of the vast Alumni network, so a reputable MBA program or MBA program in a reputable university is more desirable than the others.
Michigan is good for both MBA and university, while Oxford is the one of best university in Europe. Thus, it is a choice of yours,