I think the worst is the lack of support for 'click-through' behavior on MacOS. This is that you have to select a window first with left-click before being able to select UI elements within that window with left-click. The amount of time lost with extra clicks is incredible.

It is even more frustrating that this behavior is somewhat inconsistent, with some applications allowing this and others not (although it is more often the latter).

I made a workaround solution here with minimal setup/overhead: https://github.com/dainank/apple-click-through but I do wish someday this could be configurable in the OS as a setting.