I see Jellyfin suggested as an alternative to Plex here. I hope it is one day.
At the moment it’s nowhere close.
I’ve been running Jellyfin side-by-side Plex for two years and it’s still not a viable replacement for anyone but me. Parents, my partner, none of the possible solutions for them come anywhere near close to the usability of Plex and its ecosystem of apps for various devices.
That will likely change because plex is getting worse every day and folks can contribute their own solutions to the playback issues. With plex it’s more noise, more useless features. So one gets better (Jellyfin) and one gets worse (Plex).
But at the moment it really isn’t close for most folks who are familiar with the slickness of commercial apps.
Even from the administrative side, Jellyfin takes massively more system resources and it doesn’t reliably work with all my files.
Again, Jellyfin will get there it’s just not a drop in replacement for most folks yet.
And for context I started my DIY streaming / hosting life with a first gen Apple TV (pretty much a Mac mini with component video outs) that eventually got XBMC and then Boxee installed on it. I even have the forksaken Boxee box.