ive been using kodi (xbmc was better moniker) since google killed sagetv. i recall attempting plex, but it seemed to lack some open/extensibility (its been awhile).
i have a side project i want to make as a modular plugin generating a cable layout with original air orders and networks/channels... kodi seems most optimal, but ill admit its been a long while since i looked at plex.
Kodi is horrible on touch devices. I also don't want to have terabytes of files on every device I want to watch something on. Sure, there are workarounds, but I could also just use Jellyfin. Yeah I don't use Plex, I use Jellyfin.
But it's really just mainly because I dislike the UX of Kodi.
Streaming a full 4k movie rip takes more bandwidth than most people would have available on the go. Plex/Jellyfin can offer transcoding on the server for such usecases.
Plex originally was a fork of XBMC for MacOSX and had the name OSXBMC, but I doubt they nowadays use a lot of code from XBMC
Kodi is the new name of XBMC
Jellyfin is a fork of Emby, but Emby isn't a fork of Kodi/XBMC. It's even written in a completely different language. People were mad that Emby went closed source, so they forked the latest open source code and called it Jellyfin.
Don't it work with real-debrid though? I'm considering getting back into streaming instead of downloading, and thought this might work on Xbox for that. Last time I used it was in like 2016 with exodus