I wouldn't say helm has won, honestly. The kubectl tool integerated Kustomize into it and it's sadly way too underutilized. I think it's just that the first wave of k8s tutorials that everyone has learned from were all written when helm was popular. But now with some years of real use people are less keen on helm. There are tons of other good options for config management and templating--I expect to see it keep changing and improving.
Are there good kustomize bases for things like Redis, Postgres, Mysql, etc? My impression is that most "cloud-native" projects ship raw manifests and Helm charts, or just helm charts. By "won" I just mean in terms of community mind-share, not that they built the best thing. But I could be out of date there.
I do like kustomize, but the programming model is pretty alien, and they only recently added Components to let you template a commonly-used block (say, you have a complex Container spec that you want to stamp onto a number of different Deployments).
Plus last I looked, kustomize was awkward when you actually do need dynamic templating, e.g. "put a dynamic annotation onto this Service to specify the DNS name for this review app". Ended up having to use another program to do templating which felt awkward. Maybe mutators have come along enough since I last looked into this though.
