Celluloid (formerly GNOME MPV) is a simple GTK+ frontend for mpv. It aims to be easy to use while maintaining high level of configurability.
Configuration files: Celluloid is capable of using mpv’s configuration files as-is. Keybindings can be set up using mpv’s input configuration file.
Drag and drop playlist: The playlist entries can be added, removed, or rearranged easily with drag and drop operations.
MPRIS2 support: Celluloid implements the MPRIS D-Bus Interface. This allows for better integration with desktop environments that have compatible MPRIS clients.
Wayland support: Celluloid is fully functional on Wayland.
After testing multiple video players, this is for sure the easiest to use and the most functional.