Those don't run on Linux, but they're basically the same.

On Windows, Flameshot's installer is 40+ Mb, while Greenshot is 1.8 Mb. ShareX's installer started small, but has grown steadily up tp 7 Mb. I know installer size is not equivalent to performance, but on limited machines I stick to Greenshot, which works well for my use cases.

They all do the same thing. Flameshot has the cleanest interface IMO.

Not entirely true; ShareX has many more features than Flameshot, including video capture and custom uploaders.

Love sharex. The gif feature, region capture, image editor etc makes life a breeze.