Yeah, I've heard of jellyfin, but don't really know anything about it... How is it different?

I'm likely to stay with Plex though, because I have 3 friends with Plex servers and we're all sharing content. It's pretty fantastic, when I don't have something, usually one of my friends does have it. If jellyfin doesn't support content sharing, it's a huge no-go, but just convincing my friends to switch over would be pretty challenging.