In my experience as both a student and an educator, students are far more excited to participate in an activity that they have some level of skill in. Whether it's a sport, academic organization, music, or something else, students enjoy the experience of seeing the work they put in become something great. For that reason, I focus on growing students' practical musical abilities first and foremost. Helping students become better musicians certainly seems like an obvious thought process to have, but there are plenty of other focuses that some music educators have had in my experience. Some choose to focus solely on their students having fun and therefore have them play only pop music or movie soundtracks, others put all their effort into making the band room a social hub in which students feel comfortable. I, however, see these as sub-goals that come with skill enhancement.
Students don't choose music because they want to hang out with their friends, they could do that anywhere else. They don't choose music to listen to pop music, they could put in their earbuds and play it on their phones. Students choose music for the music. They stick with it for the feeling of accomplishment when months of practice and rehearsal leads to an excellent performance. They stay for the joy of looking back at how far their skills have come from when they first started. Students play instruments and sing for the ecstasy of decorating the passage of time with their emotions and effort. The very best way for students to have fun, feel accomplished, feel seen, and to thrive in a music classroom is for we as music educators to push them to be great in whatever aspect of music they love.