If you are looking for a gaming monitor that is capable of offering great performance in 4K, then the one you should go for this 2020 is the Acer Nitro XV273K model, as it is currently available for a smaller price.
The Acer Nitro XV273K is a brilliant monitor designed for gaming, and it supports native 120Hz variable refresh rate with support for both FreeSync and G-Sync technologies. Note that it also supports 144Hz via dual-DisplayPort connection, but that will disable the FreeSync / G-Sync support. There aren't too many differences between running 120Hz vs 144Hz, so you are fine running the native refresh rate with FreeSync/ G-Sync features enabled.
The native 120Hz variable refresh rate is supported through a single DisplayPort cable. If your computer is capable to run games at over 120fps at 4K resolution, then you won't notice too many issues with the
The Acer Nitro XV273K features the following specs: 4K UltraHD 3840 x 2160 screen resolution, IPS panel with support for both AMD FreeSync and Nvidia G-Sync technologies, DisplayHDR 400, QuantumDot technology for better color accuracy, 1ms response time, two 4W audio speakers, DCI-P3 90% wide color gamut, one DisplayPort 1.4, two HDMI 2.0 ports, and four USB 3.0 ports.
This monitor is currently available for a smaller price, as you can get it by paying $700. We don't know for how long will this deal last, but it is still $200 cheaper than the original price. If you are looking for a good 4K UltraHD monitor, then you can think about getting the XV273K monitor.