As someone who spent several years with the State Department I can tell you that AUB is very well regarded. Keep in mind this is a professional opinion, not academic. Although known in government/policy circles, many outside the USG may not be familiar with it.
On the other hand, there is AUC. Not only is it very well regarded professionally, it also has a solid academic reputation. In fact, the former dean of Columbia's SIPA now serves as its provost.
If I had my choice I'd go with AUB.