I use MPV as well (local build of the release 0.17.0 and all of the additional components it requires using compiler flags -Ofast -march=native) and have the best results with it so far. But you need to configure it properly, at least set it to use the Video Toolbox framework for the decoding acceleration.
here's part of my config -
~/.config/mpv/mpv.conf
Code:
# Video
# OS X 10.8+: VideoToolbox
hwdec=videotoolbox
# Video Output
vo=opengl-hq
#vo=opengl
If you want even better performance (but the difference doesn't seem to be very big) you may use the video output mode "opengl" instead of "opengl-hq". You may also try to add the videotoolbox-format option and try how it performs with different values (nv12, uyvy422, rgb0). nv12 is the default one and usually provides the best performance.
See
https://mpv.io/manual/stable/#video and
https://mpv.io/manual/stable/#video-output-drivers