I recently purchased the Sony X800D from Best Buy at 43" 4K HDR. It has a nice picture, blacks are a little grey and washed out but the backlight is very nice with no PWM and the size is perfect for a computer monitor 4k at 43". However I previously had for about a month last year the 48" JS9000 which had an amazing picture across the board, black blacks and really bright and stunning HDR and colors that popped.
I am torn between the two screens at the same price - $800. The Sony HDR has not nearly the pop. I mainly use it to play games like Doom, witches 3, and a few others. Have a gtx 1080 so frame rates are pretty good at 4K. But I also like to watch amazon prime and that is where the HDR matters, and future games will look better also.
Do I go for the better contrast and HDR with samsung? Or the better dpi and no pwm on the sony? Tough call. I have to say I am leaning towards getting the samsung again at $800, as that picture was killer even slightly seeing the pixels.
You had the Samsung. Did the PWM bother you? If yes, then you shouldn't get the Samsung, there's no point in buying something you'll be unhappy with.