Helm isn't great (god, Go templates, shudder), but I love being able to bundle all the manifests for an application together with well-documented parameters/values... If you want do something like conditionally switch from a LoadBalancer service to Ingress in a test environment... I have no idea how you'd handle that in Kustomize, but it's straightforward in Helm. Ultimately it seems like you end up with the same complexity, just expressed via 100 layers of Kustomize transforms instead of with a conditional in your template.