The most ideal synchronization status for Security Management Server High Availability deployment is 'Synchronized'. Synchronization ensures that all instances of the Security Management Server have the same data, which is critical for maintaining consistency, reliability, and security across the system. States like 'Never been synchronized', 'Lagging', or 'Collision' would indicate issues where the servers do not have up-to-date or consistent data, potentially compromising the effectiveness and security of the deployment.