Thread appears to be winding down, but can’t let this quote go uncontested. Any undergraduate intent on graduate school should make every effort to participate in research and publish their work. Participation in undergraduate research and authorship on a research paper is probably the single most important thing a student can do to boost their chance of admission to graduate school. Heck, these days many * high school* students are co-authors on papers.
Leiden rankings are probably more informative for STEM majors: http://www.leidenranking.com