For a long time I didn’t bother having any type of media server at home, I just had the machine that had copies of my media hooked up to the TV directly or had a computer sitting on that TV accessing the media through a SMB share or something along those lines. However since that didn’t really provide a user friendly interface I eventually wound up looking into options.
For a long time I ran Plex internally, it was well supported and worked on my Apple TV devices, as well as the Chromecast devices that I used for a long time. The one thing that started to be a issue was Plex pushing subscriptions more and more aggressively over time. Now to be fair, I wasn’t paying anything for the service so it’s not something that I can really complain about however when I started looking at getting hardware encoding enabled and found out that it and the mobile apps were paywalled behind a plex pass or some other type of payment I wound up setting up a Jellyfin instance to see if that worked better.
Install for either was pretty simple because both were installed in Docker containers on the server where my media lives, so for the most part it was just pick the correct image, set where the media lives, and go. Now, if you where installing on something other than a Docker host things might be a bit more involved and in that case Plex would probably have the advantage depending on what you are running on. The UI for both is good enough, but Plex is a bit more polished. That said, i’m using this as a media player so I won’t be spending a lot of time in that UI (hopefully).
The biggest thing that Plex seems to do well is support for various platforms. From what I’ve seen it’s got clients for most everything out there where Jellyfin is a bit more… selective in what it supports. In my case the streaming devices that I’m working with at home are supported so there’s no huge difference for me. It does however mean that if I’m replacing a TV or streaming box that I need to make sure that a client for Jellyfin is available for the device. Right now that’s somewhat limited, but at least Android and Google TV are supported so there’s decent selections of devices around. Plex however supported a lot more devices at the time, so if you aren’t willing to look at replacing your Device that might be the deciding factor.
In the end Jellyfin did everything that I need, and it supports the devices that I have around the house so I’ve moved everything over and shut down the Plex instance that I was running.
Your milage may vary, however when I can use a free, open source, option over something that potentially costs me a fair plile of money I generally lean towards the free option. That said I did pay for a Unraid license instead of going with TrueNAS on my primary storage server for a reason.