Best International School (Bilingual program)

My son got an offer at the Canadian International (CDNIS), HKIS, GSIS, ESF and SIS. He can speak fluent Mandarin and English.

I want to send him to CDNIS as they seems to have a very well balanced program of both Mandarin and English. SIS seems too strict and too many SE Asian nationality. I want him to grow up in a multiple nationality enviornment. The ESF Kindergarten seems to have over 95% local students and they hate to speak cantonese to each other. GSIS has excellent academic results but either me or my husband are German or Swiss, so its not an option.

if anyone heard or have view on these view schools esp the CDNIS would be much highly appreciated. Thank you!