My personal take is as follows so feel free to get offended at your own discretion:
A. Samsung Q90R. It's *only* use case is bright viewing in a reflective room. If that's your main use case, go for it! As soon as lights go dim or it's asked to handle dark content, it's game over. I have no idea what it costs but unless it's 50% lower than the cheapest OLED on stage, absolutely no would be my take on this.
B. Panasonic GZ200. Very solid all around. The two things that I would have a hard time getting over; it's over dimming of static logo's and it's banding issue due to Panasonic over driving the panel to hit high nits. Both pieces are clearly visible and would start grating after a while. Price difference is virtually impossible to justify.
C. LG C9. Easily the star of the show. Either on par or ahead in most areas. The set I'd take except for one big issue. Vertical lines on black content. Vincent mentioned that was the 2nd panel and the 1st one had even worse lines. If this is a LG processing issue, I'd be concerned. Lower on the list is the low apl handling of highly compressed dark content such as S8 Ep3 of Game of Thrones.
D. Sony AG9. It's failure on HDR tone mapping is unacceptable and the fact that Sony doubles down on it's being the right way tells me it's not for me. It's smooth gradation advantage of years past has been more or less matched by LG now. Hard to say what they're left with at this stage unless you have a preference for their method of HDR.
As standard definition content becomes a thing of the past, upscaling of standard definition has little to no relevance and all the sets did a great job of scaling up 1080i/p content to 4k so no real magic to be had there.
