SFML uses degrees. In my experience, it's the only thing that uses degrees (except for old, deprecated, and removed OpenGL stuff, which I ignore in this modern era).
I always use radians for things. Standard C and C++ trig functions take radians. OpenGL shader trig functions take radians. HLSL trig functions take radians. Whenever I do various geometric things I use radians. Honestly, the only time I ever "use" degrees is when I'm reporting them to the user; but even then I'm not really using radians; I'm just formatting the number as degrees for printing to screen. Whenever I actually use an angle, I use radians.
What about others? When do you use radians? When do you use degrees? How often do you need one or the other?
Side note: this isn't a "SFML should use radians" feature request, so I'm not looking to debate whether SFML should be radians/degrees. That kind of debate can happen in another thread. I'm trying to understand what users of SFML use, in real life.