Helm is so bad it raises my blood pressure just hearing the name. Helm tries to apply the old way of doing things (like as you said Puppet) and makes it worse than ever. K8s yaml config is simple and elegant, don't try hiding it under templates. Kustomize is the proper way of working with K8s yaml. Helm fights against it.
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.
There are two different types of patches in Kustomize. It does take a bit to get used to it as it's different. jid (Interactive jq) makes the process a lot easier. It's actually pretty easy to make changes like this.
