The most infuriating thing about Plex for me was when they shifted to force you to start with their BS streaming service at open. I only used Plex for my personal media collection. So having to jump through a bunch of menus to get to the only thing I want to use in their app was the biggest reason to switch for me. Maybe there is a way to fix that, but I could never find one.

Jellyfin just does your personal media library and opens right up into it when the app starts. Its simpler, faster, and FOSS.