The most valuable features of Istio are the traffic management and the Sidecar they inject, which greatly helps secure the application. Istio saves time in a more secure way. Since it saves time, we can focus on other areas while writing the code. The solution's security feature or mutual TLS authentication helps a lot in controlling the access policies.

We use Istio for Service Discovery and routing traffic.

Istio can save you time in terms of network troubleshooting. It gives you a clear indication of how the data is flowing with the commands in the Istio service commands.

The tool's mutual TLS stands out. It provides secure communication between services within the cluster. Additionally, Istio offers built-in telemetry and tracing with tools like Jaeger, which aids monitoring and troubleshooting. 

The load balancing, service application, and monitoring of the life of the service are valuable features. We use it for authentication of call services, load balancing the calls among the service providers on service instances, and monitoring the health of the services.

Istio's best feature is that it's easy to use.