I have yet to come across a study on this issue. I do know that in law school, it is not uncommon for students with lower LSAT scores to be admitted over their better-qualified peers because of other factors such as commitment, communication skills or work ethic. And when you are working at the bar exam, judges often look beyond your score alone when deciding whether they should allow you to take an oral argument before them during the bar exam process.
It’s also important to remember that any lawyer who has spent even a few years practicing law is familiar with many different kinds of practice areas (e.g., criminal defense; divorce; child custody; bankruptcy; real estate closings); therefore, there is no “best” path toward becoming an attorney. Rather than focusing too much on one path and hoping for success in one area, all lawyers should focus on accumulating experience in numerous different types of legal practice (e.g., contract negotiations). The more diverse experiences you obtain while doing this type of work, the more successful you will become at running up positive billable hours and generating revenue through new clients and repeat business from existing clients alike.