I would say PowerBI has the edge in ease of integration but I’m a little biased. I do have experience with Tableau and my recollection was there are many challenges in their API from methods that are not available in the REST API to the server requirements. I think this integration awkwardness stems from the legacy of Tableau which dates back to the 90’s.
As of 2024, Tableau's easier because there are some Web Data Connectors that exist for it. Airtable Labs have one which is free.
We built our own Connector that supports the full range of many-to-many relationship types, including Multiple Linked Record fields and Multiple Users fields. So you can build Tableau reports off of your Airtable data even when your Base contains these many-to-many relationships.
Nice thing about Connectors are they're 100% secure - data flows directly from Airtable to Tableau without ever touching third party servers.
Link to our landing page is here (there’s a 30 day free trial) if it's of interest.