Birmingham or Bristol?Watch
The University of Birmingham is a campus university. Thus, all facilities and services are self-contained, and you may be able to survive without ever leaving the campus. The student population will therefore be much larger as you enter the University campus site. Whereas, the Bristol site has been spread over several miles, and it therefore does not appear to be as student populated en masse.
The nightlife of both cities have been deemed to be outstanding, however, having been a resident in Birmingham, I would assert that this city has the edge when we consider factors such as the student experience. It is England's second city (with great shopping facilities such as the state-of-the-art shopping centre-Bullring), is rather multi-cultural and multi-racial, whereas Bristol does not have the same extent of multi-culturalism, which may be a factor to consider.
Bristol feels more like a town rather than an industrialised city. It has a reputation of being very artistic, with famous Barksy'art originating from here. It is however, very hilly!
Both Universities are fantastic, yet different. I would advise you to consider the structure and reputation of their course, and perhaps the unique opportunities that both offer.