It's a long list. Most prominent lately, for me:
* uv/poetry detection and environment use
* refactoring
* unittest/pytest support
* docker compose service support (e.g. if I have a docker-compose.yml file in my project directory with redis and postgres services, pycharm lists the services in a UI and lets me start/stop/restart them easily from the IDE.)
* django app/model detection and completion from those models as I'm building things that query them
* "compound" runners, so I can start a npm watcher and a python watcher at the same time, and bounce them together as I iterate
* The debugger is really, really good. And it's practically automatic to jump from the PyCharm debugger to the Clion debugger when I'm dealing with a python package that has C++ modules.
* django and jinja template support as I build out things that present my results.
* ability to connect it to a data source and query/explore using sql directly against that, and see tabular results to help guide my other explorations
* Vim emulation in the editor... IdeaVim is a really good vim implementation, and I find I hate working without vim movements and commands.