I will have to disagree!
I chose Aston, after visiting both universities + interview at Birmingham and am very happy with my choice.
Birmingham is a massive and beautiful uni, lovely grounds, etc but Aston just had that edge over Birmingham. Oh plus the small fact that they could offer me accommodation almost immediately! Whereas Birmingham basically told me they wouldn't have anything for home students!
Many of my coeds also considered Birmingham but chose Aston. Aston is a much smaller - but I like that. The environment is very supportive, I just felt more comfortable here. But hey everyone has their own preferences.
Aston also runs an intense personal development and strategic career management programme alongside the our academic modules, which was something that was also important to me.
Re the accreditation - if you're going to spend thousands on an MBA you will as well pay to do it at a highly accreditated institution. It's not the most important thing but it is a another seal of quality, especially from a potential employer's point of view.However Birmingham has a good brand in the UK so I think that probably overrides the lack of AACSB.
Hope you're enjoying the course susee :-)