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.
My issue with Kodi is that each client had to scan the library and generate thumbnails etc. That should be the server's job which is why I chose Jellyfin. Nicer UI too and more responsive with apps in stores so I don't have to load it manually to fire sticks