If you know somebody is going to be awfully annoyed by something you write, that's obviously very satisfying, and if they howl with rage or cry, that's honey. ↗
I found collaborating with congenial doctors about problems that physicists could help solve was very satisfying. I also like educating anybody who would listen! ↗
So, for me, working with larger companies has often been very satisfying, precisely because of the ability of bringing critical mass to bear on a given effort. ↗
A non-fiction writer pretty much has the shape of the figure in front of him or her and goes about refining it. A work of non-fiction is not as difficult to write as a work of fiction, but it's not as satisfying in the end. ↗