Most pre-meds are incredibly anxious about where they will get into medical school. This is totally normal, since only 43% actually get in to allopathic school. As a result, pre-meds pick medical schools based on where they hope they can get in rather than thinking about where they actually want to go. The problem with this line of thinking is that it doesn't help you get in.
Choosing schools this way would be like buying a car without figuring out whether the car does what you want it to. Sure, all cars get you from point A to point B (just as most med schools will allow you to become a doctor), but there are tons of features to consider.
Manual or automatic?
How much trunk room?
How reliable is it?
What's the gas mileage?
How much does it cost?
Whether the car is a good fit for you depends on your preferences and how well they align with what the car does. Like cars, med schools have meaningful differences that you need to know about before you apply. There are 141 allopathic medical schools, and the more you discover about their differences, the more likely you will be to get in. By finding where your experiences and aspirations would be a good fit, you are better able to show the medical school the kind of impact you would make at their school.
For example, let's say that you spent 6 months living and working in a hospital in Guadalajara, Mexico, building connections with the patients, speaking Spanish to your patients, and helping to improve the local community. You have identified several medical schools with global health tracks that would allow you to return to Guadalajara to do some clinical research or maybe spend time in a different Central American community doing something similar. You are more likely to get into that medical school because of your unique experiences that would help contribute to that program.
So, the more you identify the connection between what the med school has to offer and your background, the more likely you are to get in. What other factors should you look for to help distinguish the schools on your list? Specifically, consider:
Location – is the school located in an urban area with a diverse patient population? A rural area with more chances for hands-on interaction in primary care? Are there specific communities that you would be interested in getting involved with?
Curriculum – how does the school teach its science classes? Organ-based systems? Is there small-group, problem-based-learning? Does the school offer an opportunity to get early patient contact? A research thesis as part of its curriculum?
Residency placement – Looking at the residency match placement list for the school, do the results look good? Are there people in the areas that most interest you?
Class size and student-faculty ratio – is the class small? Would you get a chance to interact with faculty?
Student groups – looking at the list of student groups on the school’s website, are there specific ones that you could see yourself getting involved with?
Research - are there research projects at the medical school that you think you could contribute to? Does the school have NIH funding in the areas that most appeal to you?
Mission Statement – does anything appeal to you about the school’s mission statement?
Overall – based on the school’s website, what are the things the school prides itself on? How does that match with what you want from a med school?
There are plenty of other factors you could consider as well, so use the list above as a jumping off point. And to play devil's advocate, it's probably true that you will end up going to the cheapest and/or "best" school you get into. If you get into, say, Cornell and Temple, you're probably going to Cornell (I don't mean to pick on Temple; it's just not as highly ranked as Cornell). But this is mostly a numbers consideration - either you have the GPA and MCAT to get into a certain school or you don't. By doing your research, though, you can help find which of the schools where your numbers match you are most likely to get into. And THAT will make you more likely to get in.