I would agree with the earlier respondant that political science is probably the most popular/traditional. I chose that major for my undergraduate degree. However, I chose it because I was interested in the subject not because it was necessarily the best major. I think political science will help prepare you for essay exams. With that said, law school essay exams are different than any other exam you will ever take. So my recommendation is to study something you are interested in. I think people do best at subjects they are interested in and it won't seem as if you are laboring trying to get through the material. Another suggestion is to find law classes taught in different subjects and take them as electives i.e. Business law, Constitutional law etc. These classes will help prepare you for the material as well as help you decide if you want to pursue law in general. I hope this helps.
Surprisingly, some legal professionals argue against choosing a pre-law degree. U.S. News & World Report states that a 2011 LSAC study revealed that only 61 percent of pre-law students gained law school admission, whereas philosophy, economics and journalism majors all had acceptance rates over 75 percent. Though it seems counter-intuitive, aspiring lawyers may be best served to forgo an undemanding pre-law degree in favor of a more challenging single-subject major.
The most common route is to major in Political Science, with something in Pre-law.
But because you can be an attorney in any field don't feel pressure to go that route. I have friends who started their careers as pilots, and after law school practiced aviation law. Or grew up on a farm and do animal law. The most important thing is to take courses that require you create "logical arguments." This could be courses in psychology, philosophy or even something in the sciences.
Couple of other pieces of advice:
Look for hands-on experience: intern at a law firm or legal aid
Be active the world: volunteer in your community or on campus.
Improve your standardized test skills.
Practice public speaking and writing.
You only have one chance at a college experience. Take courses that interest you. There is no such thing as pre law classes that will help in law school. Grades are all important. If there are no courses you love take easy cours