my understanding is Polars is faster, scales better without using external solutions, better API, +Rust. Pandas wins if you want to use what the vast majority of folks are using and have used in the past. Probably has a more complete set of helpers / recipes for the little things you bump into when using it thoroughly, but in the age of LLMs, I think that's minor.
It’s the API that gave me the push to leave Pandas. 10 or more years of occasional Pandas use and I still had to google for any non-trivial queries.
In that regard, I’m still waiting for a credible jq replacement…
Avoiding pandas developers is a great reason to use polars imo
>Pandas wins if you want to use what the vast majority of folks are using
Vast majority of skilled developers are now using Polars, unless they are constrained by lack of Narwhals support in their third-party library of choice (e.g. Great Expectations, SHAP). That's the more important trend to follow.