HIK NVR is for HIK cameras, Dahua NVR is for Dahua cameras..
main difference is in what ecosystem you want to live (camera, NVR, UI/UX, mobile app)..
this forum is mostly Dahua forum, so You will not find here big love for HIK..
HIK M-line is not AI NVR (like HIK Acusense or DeepinMind...