Hi again, I wanted to follow up on this topic. I have generated a small “real world” state diagram with the different methods discussed. I wanted to share their output and visually compare them here. – Maybe someone is interested in this. The diagrams show always the same states and transitions.
Diagrams
First the state diagram with plain labels on the transitions:
Then the state diagram with (HTML-table) boxed labels on the transitions:
Additionally here the state diagram with “decorated” labels on the transitions (see decorate | Graphviz):
And finally the state diagram with the transition text in their own (differently styled) nodes:
Discussion
I think I will go with the last version (transition text as nodes), despite the fact that in this version nodes are not anymore only for states reserved. IMHO it is still a bit cleaner than the other options.
Runner up is the first version (plain label style) which, I guess, Graphviz itself suggests. The other two versions appear to me to busy and distracting.