I hate Plex. It's gotten too bloated.

I run Emby primarily, but not externally accessible [vpn]. It works really well for me, haven't had any issues.

I use Jellyfin to put some stuff for the toddlers. It works on Amazon Fire Kids, while Emby doesn't. It works ok, but it's definitely less polished than Emby, and I feel like it's not as stable. Could just be me though.