I’ve only used Jellyfin, but it does everything I need it to really well. It’s a fork of Emby so it would probably be a pretty easy transition if that’s where you’re coming from. Jellyfin gives you a lot of control over things which is both a blessing and a curse, but I don’t think it would be too much coming from Emby. I think if you want an app that works anywhere, go with Plex, but Jellyfin is working on getting on more devices and while some apps are better than others, the Roku app is their most mature and I’ve really enjoyed using it.

I’ve heard pretty good things about Plex, but I think a lot of the features are blocked behind a paywall. Hardware accelerated encoding is one feature that’s locked on Plex but available on Jellyfin which is what got me to go Jellyfin.

I can’t really speak on the multiple users since I’m the only one that uses my instance, but I’d assume that would come down to your hardware more than the particular software you use (I could be totally wrong tho).

And for file management, do you mean like grabbing metadata and thumbnails and such? If so, Jellyfin does a great job with that. It uses TMDb by default to get all of the movie info (synopsis, cast, crew, year, etc.), but you can use whatever database you want. It also makes it really easy to find movies that it misses or gets wrong. You can either use Jellyfin to search a database and choose the result manually, or plug in the movie id from a bunch of different databases (including IMDb) and I’ve never had any issues with it finding the right movie. If you mean actually managing the files on your hard drive, I can’t really speak to that. I try to keep things super organized myself (with some automation from Sonarr/Radarr) which makes things really easy for Jellyfin to find everything and do its thing.