You would use Snowflake over Azure Synapse Analytics when you need a highly scalable data warehouse that can automatically adapt to varying workloads without manual configuration. A specific scenario would be a fast-growing e-commerce company that experiences seasonal traffic spikes; they could benefit from Snowflake's ability to scale compute resources automatically to handle the influx of data during peak times.
You would use Azure Synapse Analytics over Snowflake when you need a seamless integration with other Azure services or when your organization is already heavily invested in the Azure ecosystem. It's particularly useful for scenarios involving heavy data processing and analytics workloads where you want to leverage the capabilities of both data warehousing and big data analytics in one solution, such as building an end-to-end data pipeline that connects data ingestion to real-time analytics and visualization.