As lousy as Plex (both the company and the product) have become, there really aren't alternatives with feature-parity available. Jellyfin is starting to get there in terms of basic media center functionality, but still faces stability and platform compatibility issues that have been long-solved by Plex. Jellyfin also lags behind in ecosystem support/integration for those of us operating media servers with heavy amounts of automation and dependencies on workflows executed by 3rd party packages.