> What is the most used/popular desktop (web) screen reader out there?
On Windows, JAWS[1] and NVDA[2] are the most popular, the latter of which is open source. On MacOS, the only choice for GUIs is VoiceOver[3].
[1] https://www.freedomscientific.com/products/software/jaws/ [2] https://www.nvaccess.org [3] https://www.apple.com/voiceover/info/guide/_1121.html