The most popular majors vary every few years, but according to National Center of Education Statistics business, health professions and related fields, social sciences and history, psychology, biological/biomedical sciences, engineering, visual and performing arts, and education rank as the top 8 major choices.
Popularity of these majors deals in part to the number of factors including the number of colleges/universities offering these programs, career/financial prospects, personal interests, and ease of completion.
If you're trying to find a major - pick something of interest and see if you find success in the class and the interest continues. If not, no worries - a large portion of undergraduate students switch majors during school in an effort to find the right match.
Hope this helps!