As an entering pre-med track student. Is it better to major in biology or a smaller section of biology (microbiology, molecular biology)? Which will prepare me for medical school the most.

As far as preparing for medical school, you could look at the basic science curriculum for the school(s) you would like to attend. Any coursework you do that matches the courses in the med school curriculum will leave you better prepared in the sense that you will have studied the material before. On the other hand, it is certainly possible to take the bare minimum prerequisites for admission (biology, general chemistry, organic chemistry, +/- math and physics depending on the school) and be adequately prepared for your med school courses. You would just be learning rather than relearning.

I studied electrical engineering as an undergraduate. There were plenty of students in my med school class who studied biochemistry, histology, anatomy, microbiology, etc before med school - often at a graduate level. Having that experience certainly made the course work easier since they'd done it before. However, I still value the analytical and problem solving skills I learned in engineering school. I also have a much better understanding of all the technology that is so much a part of medicine today.