Azure Kubernetes - Azure Monitor & Sidecar Logshipping?

Azure Monitor collects logs and sends to Log Analytics workspace. It can't send logs to ELK stack. So if you are used to these tools and want to continue using them then fluentbit sidecar or fluentd daemonset based solutions are alternative. But management of ELK stack is on you in this case.

The advantage of Azure Monitor is that it consolidates your AKS logs with other Azure platform logs, providing a unified monitoring experience.

The disadvantage of azure monitor is that at very high volumes, cost may become a consideration.

So you may want to use open source ELK stack for applications which produces high volume of logs and use Azure Monitor for applications which produces low volume of logs.

Just to add another option to Arghya Sadhus answer: Elasticsearch has a rather high memory footprint in production ready installations. And personally I think it's overkill to use it solely for log aggregation.

A lightweight alternative is that you could use Loki which integrates directly in Grafana to aggregate your logs. (See here for reference: https://grafana.com/oss/loki/)