Upscaling are fairly similar across all the major brands , Samsung likes to stretch its screen by overscanning but unless you are using magnifier to spot the difference , I doubt you will see it .
Since you are mostly eyeing on the basic 4k models , I suggest you get the Sony XG70 instead .

It is equipped with WCG and is the brightest among the 3 , which translates into better HDR TV .

(Again , don't expect good HDR at this price range )
X8000G = basically like X7000G running on Android OS , with more HDMI 2.0 ports and other trivial things.

X8500F & X8500G = Sony's 2018 and 2019 mid range TVs that are slightly brighter than XG80 , with a 120hz refresh rate and native 10 bit panel .