I use both, I have had my plex running since the lifetime pass could be had for 40 bucks on sale.

I still use plex because it Just Works™️ for my family members. But, the day when they suddenly unprompted blasted all family (and me) with emails about what everyone else watched this week, I decided I would never use it again myself. I also told my family that the next time that stupid ass plex database gets corrupted, I’m not restoring it and they’ll have to join me on jellyfin.

I started using Jellyfin for myself, and I absolutely love it. And settings up my own preferences for transcoding, and things like that giving me full control is fantastic. But jellyfin has issues for multi users imo, sure I can manually make accounts for people and all that. But just the idea of having to input a url for the server in an app is already way past the convenience threshold for a lot.

Also most of the exposed jellyfin endpoints are entirely unprotected, and there’s no native MFA.