Comment by shiroiuma
I haven't tried smplayer, but I have used both vlc and mpv. VLC doesn't support HDR video on Linux, while mpv does, so that's a pretty big difference. With VLC, watching an HDR video results in very dark or very bad (frequently too much red) colors.
Isn't this a general X.org issue? It has no HDR support so anything you play though it has to go through a HRD to SDR conversion which VLC doesn't do very well.