it's all your preference.
the manual is here: mpv.io/manual/master/
my config if you want is this:
vo=opengl-hq,opengl
save-position-on-quit=yes
#video-aspect=16:10
# Audio
alang=en,eng,english,[eng],[Eng],English
softvol=yes
softvol-max=150
volume=100
# Subtitles
slang=en,eng,english,[eng],[Eng],English
sub-pos=98
#subs#
sub-text-font="Source Sans Pro Semibold"
sub-text-font-size=48
sub-text-margin-y=36
sub-text-color="#ffffffff"
sub-text-border-color="#000000"
sub-text-border-size=3.2
sub-text-shadow-offset=1
sub-text-shadow-color="#33000000"
sub-text-spacing=0.5
sub-auto=fuzzy
ass-force-style=Kerning=yes
demuxer-mkv-subtitle-preroll
#OSD#
osd-bar=no
osd-font="Source Sans Pro"
osd-font-size=36
osd-border-size=1.6
osd-color='#ffffffff'
osd-border-color='#ff262626'
osd-shadow-offset=1
osd-shadow-color="#33000000"
osd-spacing=0.5
osd-status-msg='(${percent-pos}%) ${time-pos} / ${duration}\n${?chapter:Chapter: ${chapter}}\n${?vo-drop-frame-count:Frames Dropped: ${vo-drop-frame-count}'
# OSC settings
script-opts=osc-layout=box,osc-seekbarstyle=bar,osc-timetotal=yes,osc-fadeduration=100,osc-scalewindowed=0.7,osc-scalefullscreen=0.7,osc-deadzonesize=1,osc-valign=1,osc-halign=1.0
#Default valign=0.8, halign=0.0
# OSD settings
osd-scale=0.7
# Screenshots
screenshot-template='~/Pictures/Screenshots/%f-%P-%[#][0X]n'
screenshot-directory="~/Pictures/Screenshots/"
screenshot-format=jpg
screenshot-jpeg-quality=100
# Streams
ytdl=yes
ytdl-format=((136/bestvideo)+(250/bestaudio))/best[vcodec!=vp9]
# Extentions
[extension.webm]
loop-file=inf
[extension.gif]
loop-file=inf
[extension.jpg]
pause
[extension.png]
pause