I use the Ofna blue 1/8 box with the one giant 12V motor in it. Turns over just about anything.
I'm not sure about the AE box. It should work in theory, but I'm not sure how torquey those motors are. Also, the MBX5 has a relatively small flywheel hole, which some people have had problems with (if the rubber wheel on your box is too big, it might not work).
One very good box is Mugen's box for 1/8 offroad. The wheel is the right size for the flywheel hole on the MBX5, it uses two stick packs, seems to be pretty torquey (even though it uses dual...550's?), and is SUPER light, especially compared to the Ofna box I use with a 12V Gel Cell in there.