I’ll ask the questions I ask Jellyfin users that, if they’re all (or mostly) yes will get me (and a lot of other people) to switch:
Does Jellyfin have:
Music filtering/smart playlists?
Sonic analysis of music to generate smart playlists?
Good 4k/x265 performance?
A third party (or built in) utility that shows me streaming usage per person? (Think Tautulli)
Allows me to limit remote users to streaming from a single IP address at a time?
Let’s me watch something together with another remote user?
Has an app for most any device (like Plex or Emby) that does NOT require sideloading?
Has built in native DVR steaming/recording support?
Two factor authentication?
Doesn’t default new clients to 720p for remote streaming?
Easy login of other devices by entering in a randomly generated four character code?