Hi @lalajee ,
To learn how to move to Azure Arc enabled servers, please refer this overview document.
As explained here, for managing the updates or patching the on-prem servers, recommended approach is using Azure Automation Update Management. However, it has a newer version as Azure Update Manager so that would be the recommendation. To learn how to deploy, schedule updates and configure reboot with Azure Update Manager, please refer this and this documents.
To answer the question on whether Azure Arc is better than SCCM/MECM for on-prem server patch management, it depends on specific requirements and environment. Azure Arc may offer advantages in terms of cloud integration, centralized management, and potential cost savings. SCCM/MECM on the other hand, is a well-established solution with extensive capabilities for on-premises systems. The choice between the two would depend on factors like your existing infrastructure, your organization's familiarity with the tools, and your long-term cloud strategy.