Tthis is a tough decision. I can udnerstand. First off, dont completely go off the rankings because they are too close to each other that it does not even matter. Second, pls do research. it will cost time but it will be worth it. you can devote all day do it and reach a more informed decision. this way you will feel better and confidence about it as well.
I would ask some of these questions:
1. which campus do you like better, where do you feel you will fit in and feel comfortable for the remaining 2 years of law school years?
2. does GMU give you in-state tuition? whats the cost difference, will it be worth it in the long run?
4. what law you want to do? big law firm? or public interest? judicial clerkship? or spmoething specific like corporate litigation, IP, human rights etc? If so, call each school's career office and ask them how many students they placed in those types of positions.
5. What if any clinics, study abroad, journals, specific curriculum (such as certificate in labor law or national security etc..) would interest you? which school is better at the things that you prefer to have?
These questions should be a starting point may be but not a complete list of things. Grade each school on each question on a scale of 1 to 5. then add the scores. the higher one will win
hope this helps.