Kodi has fallen out of fashion these days but it's also an excellent solution, depending on your streaming needs. I've used Plex in the past and found it to be sluggish on Samsung's Tizen OS. Jellyfin was a lot slicker, but also a fair bit more work to set-up if you want to stream remotely.
In the end, I put one of my pi4s to work as a Kodi box, since I only stream to my TV. It's running LibreELEC, which is a barebones OS providing just enough to run Kodi. Media is fetched from a samba share on the home server. It's been far better for me than Plex ever was, and way easier to set-up than Jellyfin. Kodi is essentially a standalone player, so not the right solution if you're wanting to stream to multiple devices or remote clients. Just throwing another option out there for anyone looking.