Moved from Plex to Jellyfin about a month ago. While it obviously isn't as polished as Plex (yet), it has come a long way in the last few years. I remember trying it about 2 years ago and the experience wasn't nearly as good.
Biggest problem for me was recognizing anime, Plex usually does a good job with it but Jellyfin doesn't. My solution is just to rename (or rather, create hardlinks with proper file names and structure) with Sonarr.
Second biggest problem has been the Android TV client. I find it clunky and the built-in video player doesn't support HDR. You can use external player (like VLC) or set up Kodi with Jellyfin add-on which I've done, but it's still not as smooth experience as with Plex.
Overall I find it better than Plex, with active community pushing new updates constantly.
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