People like VLC. Personally I am a mpv-user though. For some reason the mental model by mpv (and before that mplayer) works better for me.
On Windows, VLC is quite convenient though. While I also use mpv there, for an elderly relative I have simply used and installed VLC there, as the default GUI mode is more convenient for elderly people.
I use mpv but VLC is definitely better for people who prefer traditional GUIs, which is most people.
Celluloid and IINA are "traditional" GUIs for mpv. They work fine.