Major in what you like. So long as you have fulfilled the pre-reqs, adcomms don’t care one bit what your major is.
Both of my daughters went to med school. Their classmates had many varied & different undergrad majors: music composition, agriculture, anthropology, business, computer science, electrical engineering, English lit, geography, Italian, mathematics, physics, psychology, public health, Spanish, sociology, theology, women’s studies, as well the more usual biology, biochem, BME, chem and neuroscience.
BA vs BS–this designation is partially dependent upon the policies of the college you attend. Some colleges only award BA degrees, no matter what your major is. Some offer both a BA and a BS for the same major. BA ≠ liberal arts
As for picking and choosing from a “broad array” of courses to fulfill your medical school admission requirements—as wonderful and noble as that sounds, med schools are sticklers about what they expect from applicants: bio, gen chem, ochem, biochem, physics, calculus, statistics, English, psychology, sociology. Additionally some med schools require or strongly recommend genetics, anatomy & physiology and/or other upper level bio classes. You can’t just “pick & choose” among those–you have to take all of them.
Although some medical schools are moving to competency-based requirements and away from requiring specific courses, you still need to prove a high level of knowledge and competence in those subjects. The easiest way to do that is through coursework.