It sounds like you've done a lot of research already, so you're probably ahead of most of us in terms of specific model choices. The product lifecycle is so short that it's unlikely that anyone who's completed a build is using one of the monitors you're looking at. People will probably tell you things like "I use a different Toshiba and it's great so you should choose the Toshiba", but be cautious about that, because I've read many sources warn that there's not a lot of consistency across product lines.
You might have better luck asking the same question in, say, an Xbox gamer forum, just because the user base will probably be larger than here, and any video gamer (pinball or otherwise) will have similar technical needs for a TV/monitor.
General advice: computer monitors are likely to have lower input lag than TVs, because they won't have as much image processing designed for video (like "motion smoothing"). I don't think the same generality applies to other properties (motion blur, viewing angle) - it's just model-by-model for everything else.
I'd be a little wary of your plan to buy a 4K monitor and run in HD mode. I mean, it seems like good future-proofing to go with a 4K monitor and plan to upgrade the graphics card in the future, so it's a good plan as far as that goes. My reservation is that running a native 4K panel at HD resolution is going to require up-conversion in the monitor's electronics, which could add visible artifacts and input lag. If you have a chance to showroom any of the monitors in person, I'd make a point of trying it with an HD game input to make sure it looks and acts okay.
Edited by mjr, 30 September 2017 - 08:57 PM.