I'm also biased, and while I won't compare it to Emory for you, I will just tell you what I have seen. The attendings are exceptional, and the powers that be are very serious about making sure that the attendings are dedicated to teaching. For example, on the Tinsley Harrison service (which is the gen med service at University Hospital and one of the busiest/most intense services) the attendings have to be
invited to attend on that service, i.e, if past evaluations by residents/students show that you aren't taking the time to teach, you won't be invited. The attendings are also very respectful toward the residents and students, which is important.
Also, on my interviews I always pay attention to the residents in morning report, because these are the people that I will learn from, right? I don't know what schools all of the residents came from, but I know that the UAB residents have a knowledge base that is really impressive. I've been to some other programs where I was NOT impressed with the residents in morning report (i.e, please don't let me sit on the sidelines knowing the answer to a question that the 3rd year resident needs repeated clues to answer...

) Also, the residents seem to be genuinely happy, which is also important. Sometimes you can't really tell on an interview day, but I've been with these guys on call and after long days and they are working hard, but they are happy, which for me is huge.
All of the hospitals are either connected or within 2 blocks of each other, and you get the variety of working at university hospital, the county hospital, the VA and while you won't rotate at a private hospital, you do have the option to have your clinic at St. Vincents, which is a private hospital that is about 5 min away. And you've heard all about rankings and NIH funding, etc.
Birmingham--low cost of living, there are concerts/arts/festivals, etc, but obviously not as much going on as Atlanta (however Atlanta is only 2 hours away, so on your golden weekend you can shoot over there.)
You're in a pretty sweet position though, because they are both good programs, and you'll be well trained either way.