I'm currently struggling to fit everything I want to do into my schedule, so I was wondering what colleges see as best in an applicant: having a job, volunteering, or taking JC classes?
I think it is important to have a diversity of experiences, but experiences you can do well (so - not overcommitting and under delivering). I would not focus on the amount of activities you are involved in, but the quality as well as how you can show you've grown in that involvement. For example, I think colleges find it more revealing of someone's character if they volunteered at one place for three years and over time took on leadership roles, led projects, etc. versus someone who volunteered a little bit at many organizations but didn't show commitment to one cause or mission. Also, always tie back your experience to your future goals! All of those things are of equal value if you can share how they are helping excel your growth and future development. Hope this helps!
I completely agree with Ashley's answer. Diversifying yourself is a wonderful decision when applying to schools. For a prospective student, universities are looking for individuals that they sense are motivated, passionate and driven to succeed. If you can show your overall motivations for why you choose to do what you do on a daily basis, as well as your passion behind each of those activities (and for the selected school you plan to apply to), then you're on your way! Continue to act in ways that give back to both yourself and society, which will be apparent in all of the areas you mentioned (volunteering, working, classes, etc.). When you show your drive in any of those areas and relay that through your applications, you should be on your way to a great next chapter!