My answer: it really up to the team(s). Kustomize is more like a cluster level configuration management tool, and Helm is more used as a user app package management. I like Kustomize's simplicity, its YAML based syntax and K8s native (come with K8s). If you have one team that managing multiple K8s clusters, I think it makes sense to use kustomize, since no need to share with other teams. For tenant/users, they can use Helm, since there are many existing charts already and easy to install/uninstall with Helm commands...