I really want a 4K monitor with HDR, but the current selection isn't good enough. Luckily VESA just released a set of standards for PC monitors, so that should hopefully accelerate the process. It also doesn't help that HDR itself is still evolving, and has different standards either.
Whenever they come out with a 4K Gsync monitor with single digit input lag, HDMI 2.1, HDR10+ and at least 120hz refresh rate that's when I will make the jump. I am definitely not giving up high refresh rates and Gsync. I was a Gsync and high refresh rate monitor holdout for a few years, as I had a really nice Yamakasi 1440p 60Hz monitor with a glossy screen that was just awesome. I didn't get my current 165Hz 1440p Gsync monitor until I bought my Titan Xp, and only because the DVI adaptor the Titan Xp came with was messing with the image signal on the Yamakasi. When I hooked up the new monitor and played a few minutes of Doom, it looked like an entirely new game!
The high refresh rates literally made the game look much better and more detailed, due to less motion blur presumably. Not all games will benefit from high refresh rates as much as Doom, but yeah, it can make a tremendous difference at times.