Another thing MPV has that VLC doesn't (and almost refuses to add): Wayland support. MPV has a wayland back-end. I saw a thread where a VLC dev told a user that Wayland support wasn't coming in the next 2/3 years because they would literally have to re-write their entire back-end because it's so shit.
Note, this is coming from somebody who used VLC happily for over 2 years before finally getting into "which player is better and why".
And for those who complain about MPV not having a font-end, it includes it's own small one called the OSC (On Screen Controls). It's nothing fancy, but it allows mouse usage for the common stuff: Switching audio/subtitle tracks, seeking, fast-forward/rewind, chapter skipping