Availability Zones within a single region offer protection against most failures, including hardware and software failures, but do not safeguard against region-wide outages such as natural disasters.

Deploying across multiple regions provides the highest level of fault tolerance by protecting against region-wide outages, though it introduces higher latency and increased management complexity.

Using Availability Zones is more cost-effective and simpler to manage than deploying across multiple regions, making it the superior choice for all scenarios regardless of the company's specific needs.

The choice between using Availability Zones and multiple regions should be based on a balance between the company's need for fault tolerance, budget constraints, and tolerance for operational complexity.

Both Availability Zones and multiple regions can be part of a comprehensive high availability strategy, but they serve different purposes and are suited to different scenarios.