Completely dependent on the student student’s abilities. As noted, languages have the highest averages, but that’s because native speakers mostly take them. Spoken Chinese certainly is not “easy” for the average student. Among non-languages, Math2 has the highest average, but again, this is because very talented math students take it.
Take the subject that you know best, are most comfortable with.
In terms of what schools are looking for - depends on the school/major. Most STEM schools/majors want a Math and a Science. When one is specified, it’s usually Physics or Chem. The two History plus Literature would be fine for other majors, or to round out a. STEM application.