I don't know about jellyfin but as a daily Plex user, there are plenty of problems to solve. Not trying to extract money from me by cramming bullshit onto my home screen, not breaking every other update, not failing to stream when using the default "original quality" setting, not showing particular titles on some devices but not others, and not mistaking the Toy Story behind-the-scenes videos for gay pornography would be an improvement over Plex.