Hey together, there are advantages and disadvantages of doing both. If you do the post-bacc: you don't have any new degree to show for your work, but you might have more pertinent classes and the classes might be more geared towards taking your MCAT. I think that med schools respect post bacc grades more then they respect some graduate school grades because a lot of grad schools tend to have grade inflation. If you do the masters: you have the extra degree behind your name, which might be useful if you want to go into an academic career if you do a masters in a science, you are learning new stuff instead of re-learning old stuff, it might detract from your preparing for the MCAT and you want to be finished with your masters by the time that you enroll in medical school too. It really depends a lot on the post-bacc program and the masters program. Good luck.
