In my country, all major subjects, such as Mathematics, Portuguese, Sciences, and Social Studies, are compulsory in every school before college, whether private or not. But, in private schools, we usually have more subjects compulsories such as, for example, Music, Acting and Computation.
If I have to choose one or more subjects to be compulsory in every school even public ones, I'd choose Music and Computation, for sure. I believe these two subjects are very important to make the students understand the world around them once it became even more technological and  make them  realized how a song can be so interesting and enjoyable and at the same time so complex and mathematical.
However, I believe that everyone can choose for themselves because only you can tell what is good for you and for your future based on your preferences and abilities.