Visual process models provide support for analyzing and improving complex organizational processes. In this paper, the authors discuss differences of process modeling languages according to their ease of use and quality of user experience. These aspects are of importance for learning a modeling language, creating models, and understanding models. Modeling languages can be compared according to criteria as representational clarity, perceptual discriminability, perceptual immediacy, visual expressiveness, and graphic parsimony which are likely to influence cognitive effectiveness. In particular, they analyze the symbols sets of UML Activity Diagrams, YAWL, BPMN, and EPCs according to these criteria and discuss their strengths and weaknesses.