VLC is the install that never leaves you stuck: every format, discs, streams, damaged files. mpv is for people who care about picture quality and will touch a settings file. PotPlayer is the full Windows-style player when you want menus and hardware decode.
VLC media player
Why it won →“Opens almost any video or disc with zero fuss. Looks second; always works first.”
Alternatives
Runner-up
mpv
Tiny player with stunning picture quality.
Gorgeous picture quality and tiny footprint if you are fine with a minimal interface.
Also good
PotPlayer
Full Windows media player with power features built in.
Full Windows player with dual subtitles, hardware decode, and skins — when VLC's UI is the complaint.