Plex followed best practices and made sure that in the event of a data breach your accounts were safe, and alerted us promptly to the breach and reassured us that nothing private/of value was compromised.
JellyFin knowingly leaves multiple API endpoints with zero authentication.
I know which one I prefer, and it’s not the one with gaping security holes marked as “won’t fix”.
If you hand wave those away then you can’t possibly have any issue with Plex.