In my opinion, both SSRS and Power BI have their own advantages. SSRS provide more customization features for us to design the report, for example, custom code, many properties for each control. And it can be built to integrated with SharePoint. And Power BI can provide us interaction features between visuals, data modelling and publish to web features. For more information, you can take a look at this same thread: Power BI Vs SSRS.
Report builder is a report design toll in SSRS, which is similar to Power BI Desktop. But in desktop, we can do data modelling and data transformation while it can't be done in report builder.
In your scenario, you can chose when to use SSRS or Power BI based on your actual requirement. But as Power BI is a modern BI feature, I believe it will provide more features and be perfect in the future.
Community Support Team _ Qiuyun Yu
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