It depends on what kind of university you are looking for. If you're planning on applying to top ivy/public universities, you would need to aim for SAT 2100+ and ACT 31+. If your top choice university/college requires both SAT and ACT, you have to take both and get decent score.
Noted: good SAT/ACT are not only colleges/university are looking for, they want to know what you are doing after school such as volunteering, community service, workplace, etc.