Microsoft Certified: Azure Fundamentals (AZ-900) Practice Exam

The most beneficial kind of data storage in Azure is data that fluctuates significantly with demand. This is because Azure provides scalable storage solutions that can grow or shrink based on your requirements. When data demand varies greatly, using Azure's flexible storage options ensures that you are only consuming the resources you need at any given time, optimizing costs, and improving application performance.

Azure also offers features such as Autoscale and various storage tiers that automatically adjust to accommodate workloads that change frequently. This accommodates scenarios where data needs can spike unexpectedly, providing high availability and durability while minimizing waste in resource usage.

In contrast, predictable data or consistent small data might not fully utilize Azure’s scalability features. Such data typically can be handled by more static storage solutions, potentially missing out on the benefits Azure offers for more dynamic data requirements. Therefore, fluctuating data aligns best with Azure's powerful cloud capabilities.