What I like most about Dia diagram editor is, It is completely free to use and open-source software. It is best, easy, and very effective for making diagrams or flow of any process. I can also do object design inside it. It supports more than 25 different types of diagrams.

With a friendly and very intuitive interface, DIA has become one of the most important and sought-after tools in the world of UML diagrammers. The large number of options and the successful implementation of UML stereotypes allow DIA to be a very complete software. In addition to being multiplatform and open source, DIA allows streamlining and digitizing the flow of information between customers, systems analysts and programmers.

As a BPMN 2.0 believer, I like to do a lot of diagrams using that standard and DIA is THE best tool I've found that does that. Plus it's open source and free to use.