It's subjective, but IMO polars's APIs are better and than pandas's for ETL. Notably, pandas ported over polars's use of .col() for the 3.0.0 release: https://pandas.pydata.org/docs/whatsnew/v3.0.0.html#initial-...

Also, pandas's group_by() and window function pipelines made me want to tear my hair out while both are easy in polars.