VLC (on mobile too).

mostly use Jellyfin,
locally sometimes VLC.

VLC

mpv incredibly simple, stable, and capable

VLC for most items. PotPlayer for the most stubborn of files like TS files for easy seeking.

Plex

For media sharing on the home server- plex. Tho I'd not recommend it if you are running older techs. I hear Jellyfin is quite better since its open source and all that.
For device player Im going with MK player. Found it by a total chance in the Mircosoft store. So far it serves me well. Tried many others, but they all simply lacked the functionalities that I need

mpv/VLC

Media player classic is where its at...