VLC atm.

Still SMPlayer

Been using VLC myself for long time never had much issues

Media Player Classic Mega, been using it for years.

BSPlayer free edition - the built-in subtitle finder is useful and UHD movies play smoothly

Media Player Classic Home Cinema (MPC-HC) - Bundled with K-Lite Mega Codec Pack. I've been using it for years. I tried MPC+MadVR, but now I stick with K-Lite.

I use either Kodi as my media manager to VLC when I need to go direct.

I used to use VLC, used it for years in fact, but that all changed recently when I watched an anime and it wasn't displaying the subtitles properly, the issue was at times throughout an episode a character profile would be displayed and the subtitles would be canceled out when the character profile was shown, this was causing me to loose the plot of the story as I don't know much Japanese yet, after searching around for a different player, and I tried a few, most of which suffered the same issue, I eventually landed on GNOME MPV, it's handed everything I've thrown at it without any issue's and I'm really happy with it.

Bsplayer is fine and gets the job done in my opinion.

Pot Player