Congrats on the acceptance. I applied to South Alabama. It's a good school, as are pretty much all U.S. schools. It isn't "top-tier", but you'll get a quality medical education there. You will get into a good residency if you make good grades and perform well on your boards, and, again, this goes for pretty much all schools.
If you are ABSOLUTELY sure you want to go to medical school, and you liked USA when you interviewed, I'd say take it. Many many many people who go into college with the desire to go to med school never make it. Some of them can't cut it, and others don't make it for other reasons. If you have a guaranteed spot now, that's great.
I think a question you should ask yourself is, are you ABSOLUTELY sure this is what you want to do. Many pre-meds change their minds along the way. Don't commit to anything unless you KNOW what you're getting yourself into. It's a lot of hardwork, and, while you'll probably do well for yourself financially, you may not make as much money as you think. If money isn't the biggest factor in your decision, and you are aware of the sacrifices that you are committing to, then I guess you have to ask yourself if you would be satisfied going to USA or if you are willing to risk not getting in later to have the chance to go to a more prestigious school. Good luck.
