We are looking to configure a load balancer with some admin UI. We are currently struggling to decide between NGINX, Traefik, HAProxy, and Envoy. We will use a load balancer in a containerized environment and the load balancer should flexible and easy to reload without changes in case containers are scaled up.
You need to consider something, When these tools were created, and for what purposes? both Nginx and HAProxy were created for Web servers and Loadbalncing, a reverse proxy for Physical and VM. on the other hand, Traefik and Envoy were created for Microservices ecosystem, provides L7 routing, etc...
If you are using Public Clouds like AWS, or GCP, you may want to consider their solutions for LB, routing, etc. otherwise, you way use something else, did you consider using other solutions? check this compare and choose based on that, I would use Itsio https://stackshare.io/stackups/istio-vs-traefik-vs-envoy