I’ve used raspberry pi os and shortly arch arm, both work ok. I remeber having an issue with some python packages on arch arm, but thats it. Personally I chose Debian testing for my headless pi4 and have been happy. It’s running Syncthing, Mariadb, a few python scripts to pull data from pi pico-w. FTP server for IP cameras recording, Pydio, Pihole, and Gitea.