If your need is all about managing secrets for OpenShift clusters and just a bit about other things - OpenShift secrets is your winner there. If not - Conjur provides greater flexibility and is better choice for management of application-level secrets.
Each option solves a secrets management problem but brings a new problem - you'd have to implement and maintain it. If you consider getting help with this - check out our DevSecOps as a Service
If you are not ready to consider the implementation of a tool - you can check out our Kubernetes Penetration Testing Service.