https://thecuberesearch.com/expanding-on-execution-engines-and-composable-data-platforms/ Interesting reference on the adoption of open table formats. Looks like Iceberg is where the momentum is going:

isn't both delta & iceberg are leading from this article?

Delta has more present usage though?

Delta had more present usage, but Iceberg has more looking to use it. The survey is weird, in that it is of Databricks and Snowflake customers, so I expect higher current use of Delta just based on all those Databricks users.

what's clear is that the Iceberg REST API has "won", both UC and Polaris implement it