I've just switched to a an LG "5K2K" ultrawide [1]. 5120 x 2160 and fairly reasonably priced.
[1] https://www.lg.com/us/monitors/lg-34WK95U-W-ultrawide-monito...
[1] https://www.lg.com/us/monitors/lg-34WK95U-W-ultrawide-monito...
I cannot tell the difference between the LG and my MacBook's retina screen at my normal viewing range, but this may just be my eyes.
I also use a non integer scaling factor on both screens as I find it has the right combo of resolution and real estate for me, and I don't notice artefacts.