[_usly]

It's very difficult to find a common metric that is reliable, unless I have user generated inputs for that. Currently, it's based on Google search volume. Mostly for the domain, but sometimes that is not possible, and for Photoshop I have to use "photoshop ui design" to get a good estimate for how popular it is among UI designers.

[markestefanos]

It seems that in Figma's case search traffic will be extremely unreliable given that you navigate to the website to use it, while you use a local app for Sketch and others.