Also, you can compare math programs by popularity through IPEDS. Williams, for example, graduated 23 general math “first majors” in a recent year: https://nces.ed.gov/collegenavigator/?q=Williams&s=all&id=168342#programs.
Regarding preparation for graduate school, liberal arts college students can enhance their exposure to advanced topics in mathematics through options such as a Budapest semester or an REU, or both.