Best settings for my 1080ti

I’ve just upgraded to a 1080ti and I’m running it through an LG OLED55C7 via 2.0 HDMI at 3840 x 2160 60Hz, Highest 32bit, 10bpc, YCbCr422 and limited with HDR Game Mode enabled on the TV. However I’m not satisfied with the rendering particularly in the windows and Steam menus. Instead of blending colours together as they fade into lighter shades you can see the lines where one colour stops and another begins (if that makes sense?)

4:4:4 corrects this but then I can’t enable HDR in windows or on the tv. Which are the best settings I should be aiming for?