Well, after 4 years of medical school, here's my take on deciding which school to attend.
Regardless of how schools are ranked, I think the education delivered by the majority of schools is roughly the same. Some schools have fancy names for their systems of learning, but when it comes down to it, we generally read straight out of the same books, read the same review books, take the same shelf exams, go through the same match, and end up mixed and matched all over the country.
I personally think that success in medical school is largely dictated by the student himself. I spent the majority of my first and second years of medical school out of the classroom -- I decided to do it on my own because I found myself sleeping during lecture or playing games on my Palm pilot more often then writing down information or following along with the lecture notes. When in class, I guess I could be labeled as one of those guys who always would have asked the professor to repeat the question or say "huh?" when called upon. During the third year, I was very ambitious when it came to article searches, maximizing study time, getting involved with patient care, "challenging" decisions regarding patient care, and going "all out" to prepare for the shelf exams. Everything I did paid off and I got the residency I wanted.
It's hard to say whether I would have done the same at another school, but I think my philosophy regarding learning would have been the same.
So, I think success is less defined by the school itself and more defined by the individual's "hunger" per se.
Having said that, if most medical schools are the same in terms of education and clinical experience, it comes down to additional factors such as reputation, location, financing, family concerns, and a sense of integrating well with the current student population. I think these are important because there's NO WAY any pre-med student can get even a REMOTE idea of what any school's cirriculum is like on a one day visit. So, reputation, etc. become very important factors in the decision-making process.
If a school's reputation and financial status are equivocable, a student would do himself a disservice by considering that institution seriously, unless there are not many options.
Forget about education for a moment -- you'll do well if you make the effort, regardless of where you go. Consider everything. Some programs just shouldn't make your cut because of some red flags -- not because you might think the students at that place are smarter/dumber or the education is superior/inferior. There are Harvard students, I'm sure, who score below the mean on Step I. And there are, I'm sure, MCP students who score well above the mean.
Gut instinct is very important at this point. Think beyond the first year of medical school. Think about residency, if you can. Think about it.