Poly diploma or wait to try for JC, which path for my average O-level kid?

From my experience, follow the child's interest and learning style, not the old 'JC is more prestigious' thinking. My son was borderline too and thrived in poly because it's hands-on and project-based rather than pure exams. Poly graduates can still go to local universities, and many employers value the practical skills and internships. JC is intense and heavily theory and exam driven, which suits kids who learn well that way and are aiming straight for university. If your daughter is already more excited about a specific poly course, that motivation matters a lot at this age. Look at where each course actually leads, the further study options and job prospects, and let her sit in on open houses. There's no single correct path here, plenty of successful people came through poly.

I pushed my elder child into JC because of prestige and honestly regretted it because she struggled and lost confidence. With my younger one I let her choose poly and she blossomed. That said, JC has one clear advantage: it's the more direct route to university within two years, while poly is three years and university entry can be more competitive for some courses. So think about the end goal. If she has a clear university and career ambition that JC serves better, and she can handle the exam pressure, JC is fine. If she's practical and knows the field she likes, poly gives her a head start with real skills. My advice: go to the open houses together, talk to current students, and pick based on fit not on what looks good to relatives.