i map media folder read-only for both Emby and Plex.
Both are great with movies, poor with Series and TV Shows, suddenly they require strict naming syntax even for folder names, they mix episodes in a wrong way, can't download pictures sometimes, and no subtitles to download at all. Additionally, the cannot even play embedded (CC) subtitles (Emby).
Emby acts like it's more customizable, has plugins, although didn't really reap its benefits.
Plex setup is quite quick compares to Emby.
Plex is way way way faster in media scanning and metadata processing.
Emby plugin is constantly producing errors, and will often freeze. Really often. Manual updates especially causing freezes, and they are less comfortable. After every movie identify action, you need to restart the jail, for example.
Plex loves to force transcode, which is in my mind an operation that should not exist, i can't see any client device that couldn't handle any H264/HEVC material.
So I wanted to use Emby in the beginning, but so far Plex performs better. And DLNA players even better -- they never transcode, and always show subtitles.