Those are three schools with very different philosophies and curricula. Your experience with each will be VERY different and I'm sure the responses you get will be fairly conflicting. Familiarise yourself with the IB PYP and Montessori methods. HKIS has a strong Lutheran influence with regular chapel and religious classes (some may say indoctrination…) so take that into account as to how it aligns with your personal beliefs…I've taught at HKIS and CDNIS, my wife teaches at CDNIS and my daughter attends there (6yo as well) so I am biased toward CDNIS . Very family focused with loads of parent involvement in the school via CISPA (PTA)…and a really relaxed atmosphere…
HOWEVER…the current head of school, who is a legend there among staff and students, is leaving and a new Head is coming in for Sept…time will tell how things shake out...