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.
so why plex over kodi?
Plex has a reverse proxying service and can do upnp for you so it works with dynamic IPs out of the box with no need for a domain or forwarding ports. It defaults to upnp and falls back to the Plex hosted reverse proxy which also uses a dynamically generated subdomain and gives you a free SSL cert. Granted I prefer to host my own reverse proxy anyway with my own domain (when I had a static IP I just forwarded a port and set up an A record) but out of the box Plex does make it much easier for a non technical user to hit the ground running.
If I were you, I would just use jellyfin and don't mess with Plex Jellyfin is opensource, doesn't collect any data, and just faster in my experience
I do use jellyfin, I run it side by side with Plex on the same Intel nuc with quick sync - both with the exact same media folders added - and I let my friends choose. I don't think a single one of them prefer jellyfin unfortunately.
There is program or docker container that syncs between them. It is actually nice.
And crashes more and has more annoying bugs, that they say working as intended. The one that bugs the hell out of me is when you download another copy of an old movie it gets added to the new category. It is my biggest issue but then there is the no intro skip no screen caps well fast forwarding. And yes I know there are plug-ins for both but the authors of the players don't support third party plugins.