Glare caused by Sunlight is always distracting , even with the best anti reflection finish the picture quality will degrade to certain degree because of the strong environmental lights .
However a brighter TV can often perform better under the same situation.

If you really can't avoid the sunlights  ,perhaps you want to consider getting a brighter TV such as the Samsung's  Q9FN.
2-3 meters aren't too far away for a 65 inches  , because we are talking about a UHD TV here . If your budget allows it , the 65 inches can be more flexible than the 55 inches . But in terms of PQ they should be identical .
C8 transforms all your HDR 10 (Static meta data ) into Dolby Vision - alike HDR (with Dynamic meta data ) , so if you watch a lot of HDR content it is worth picking one over C7
Otherwise just buy whichever you can find cheaper , from a reputable source of course .

its not long now before it touch 7k, but IMO the price will rise after the implementation of SST. So the plug has to be pulled by end of Aug

A larger screen means you have more room to adjust the distance between you and the TV

Incase if you want to invite friends and guests to your house , a larger screen provide you with a wider viewing area before the brightness and colors starting to shift.
As much as OLEDS have one of the best viewing angles , the picture quality can still deteriorate when watched from the sides

Oled TV prices are expensive, any price increase by % will make the price increase very noticeable as compared to cheaper items. I would advise to buy before SST kicks in

SST does not mean prices will immediately shoot up 10%. Calm down guys.

Spent the last several days , testing my C8 . This bad boy is kicking some serious asses .
I must say I particularly love the new BFI on C8 ,  I can sit closer to the TV without getting dazzled by all the hardcore action scenes now .
Also for gamers , the new dynamic tone mapping makes a Day and night difference for gaming  . Wouldn't recommend it for movies though  , especially those mastered in Dolby vision are already very bright .
Last year they patched the OLED with a nerf on the brightness and APL , causing the a lot of games , such as Horizon Zero to look way too dark. You can offset this by turning on dynamic  contrast, however this cause a lot of details to be lost behind the brighter area.  The dynamic tone mapping is different , they analyze metadata and selectively brighten zone or object carefully with the new a9 CPU , the result is HDR highlight and zones that look a lot more iluminating than any OLED TV, yet retaining most of the fine and delicate details on screen .
I know a lot of reviewers say it isn't worth the upgrade from last year , but that is because they are not primarily gamers . For me , this feature alone is good enough of a reason to upgrade from last year's model.
My verdict : if you are a gamer , the C8 along with other 8 series  ( except B8  ) are probably the most amazing TV money can buy now  . The AF8 seem to still struggle with input lag , and Sony's OLED approach to the HDR just doesn't seem right to me , they choose to go for the brighter route and overblown the HDR details ,  one of purposes of getting a good HDR display was to check out all the glorious details behind the bright and colorful lights to begin with .

For SDR , in a darkroom you want to keep the OLED lights lower so the brightness look more comfortable (100 ~ 200 cd/m2) and natural to the eyes .

The settings suggested by rting is not very practical because they calibrate their TVs in a completely sealed , dark room without any source of lights .  I find 62 on ISF Dark room with contrast @ 85 ( ~ 200 cd/m2  )  to be perfectly acceptable assuming you have a wee bit of light from kitchen , street lamp from the window etc .

Don't mess with the Dolby Vision OLED lights setting above 50 as it changes the gamma .
LG do minor calibration for their TVs before shipping out . That's why everytime after I replaced the default OLED screens  , the settings feel a bit off and had to be calibrated again.

While this is by no means  , comparable to hiring an experienced calibrator , the out of box settings should be accurate enough for most people .
The last few % is to make your chart look prettier and the color temperature closer to 6500k , average Joes won't notice much of a difference .
If you are one of those AV enthusiast aiming to get closer to perfection , there's when you hire a calibrator . Post calibration I noticed better near black details , colors look a little more natural especially skin tones of human look extremely realistic .

Yes the motion pro is BFI , no soap opera effects but there is another problem here , the flicker is too obvious . Some people are more tolerant to flickers .
There brightness on the screen also take a hit .

This is what I use :

Picture profile : ISF Expert Dark  / Technicolor
Energy Saving : Off
Aspect ratio  : Original
Just scan : On
OLED Light  : Perfect dark room : 35 ~ , Normal Dark  / Dim room : 60 ~ ,  100 for HDR , 50 for Dolby Vision
Contrast : 85 (100 for HDR )
Brightness  : 50
Sharpness  : 10 ( 0 if you are watching ULTRA HD bluray )
Color : 50
Tint : 0

Dynamic contrast : Off
Dynamic Tonemapping ( in HDR only  ) : On ( reason to buy C8 , always leave it on )
Super resolution : Off
Color gamut  : Auto
Gamma : 2.2

White balance 
Color temp : Warm2
Don't touch the rest of the settings unless you are calibrating the TV.

Noise reduction  : Off ( low for youtube videos )
MPEG noise reduction  : On , low
*** This activate gradient smoothing at the cost of sacrificing some fine details .  Video purist suggests turning it off but I have gone through extensive amount of movies and I find this feature really helpful , the fine details removal only happen in very specific scene which is quite rare. I leave it on low .

Black level  : Low ( for full RGB , change this to high )
Motion Eye Care  : Off
TruMotion  : Off / Custom (3 , 3  or  0 , 5 , you can adjust this to your preference) . If you don't mind the soap opera effects " CLEAR " generates less motion artifact and is more usable than " SMOOTH "
Motion Pro  : Off  ( the BFI , too much flickers  for me )