Comment by zelphirkalt

Another tool, that I used in the past (though not for business, because the license is ridiculously expensive) is yed graph editor. Out of all the tools I have ever used for making diagrams, it remains the one that is the most precise, good looking results, also supports auto-layout algorithms, and makes placement and aligning things easy, as well as allowing one to import more shapes and diagram types. Over time I accumulated quite a few collections of shapes. Too bad I can't even propose to use it at any job.