Wayland just has the best multi display support hands down. (I am using Cosmic DE but KDE is similar)

Windows:

- Per-display scaling can be set to multiple of 25% (you can set more precise scaling ONLY if you apply it to all displays)

- Windows across monitors with different scaling look weird

- Mouse cursor movement across monitors based on screen pixels rather than scaled, which is inaccurate to physical distances when using monitors with different DPI

- Under the hood handles all monitors with one rectangular logical monitor, which renders a lot of unnecessary pixels in any multi monitor setups where the monitors don't form a perfect rectangle

- All monitors use the underlying refresh rate of the primary monitor for everything other than the mouse cursor (for example, if you have a secondary 60Hz monitor, timings on it will not be smooth unless your primary monitor refresh rate is a multiple of 60)

Wayland:

- Per-display scaling can be set to multiple of 5%

- Windows do not span across monitors. This can be a downside in case you want to span a window across multiple monitors with the same scaling, but is mostly an upside

- Mouse movements across screen boundaries based on actual scaled distance, so you can tune it perfectly to the physical screen distances

- Each monitor can have its own refresh rate, and windows in each monitor actually update at the refresh rate of that monitor

- Each monitor is logically separate, no unnecessary pixels rendered

MacOS:

- Similar to Wayland but per-display scaling is much more restrictive for external displays, sometimes there isn't any way to set a scale between 100% and 200% without blurring the screen

- Apple Silicon hardware also limits number of total monitors supported, so it is impossible to use big multi-monitor setups on all but the most expensive hardware