Jessetig -
Congratulations on being accepted into two fine institutions! I'm graduating from UAB in a month so I'm a bit biased. You will be well trained at both institutions. IMHO, keep in mind that both schools are in very different environments. Charlottesville is a beautiful rural college town (Albemarle county population: 79,236 in 2000). UVA shares Virginia with other excellent medical schools (Medical College of Virginia in Richmond and Eastern Virginia in Norfolk).
UAB gets referrals from all over Alabama as well as neighboring states. The Birmingham metro area is just a shade under a million residents, but covers a full range of urban, suburban, and rural populations.
Of note, Birmingham has an impressive number and variety of hospitals. UAB has the only stand-alone Children's Hospital in the state of Alabama, a full VA center, an Eye Hospital, and a county hospital. In addition, there are many opportunities to do rotations at several private hospitals in the greater Birmingham area as well as two excellent branch campuses in Huntsville and Tuscaloosa. UAB has a Comprehensive Cancer Center (with a full panoply of basic science, clinical science, and patient programs) while UVA has a Clinical Cancer Center (clinical programs only).
I would say the basic science infrastructure is far better funded at UAB than at UVA - there are more opportunities to do both basic and clinical research at UAB.
Balancing this all out is how you feel about living in Alabama. I'm an Alabama native and I love my state. However, I know that Alabama is far more conservative than just about any other locale in the US and is definitely not for everyone's taste.
If you have any more questions about UAB, feel free to PM me. I think you have two great options and I hope I can sway you to come to UAB. I am proud of the education I have received.