yEd is really great! I stumbled upon it while googling about 7 years ago, and it was awesome even then (and it comfortably beat visio). What's even more cool is their (newish) online version, which means you can do all the diagramming in the browser and even share it conveniently.
Thank you to the creators of yEd - you've put together a wonderful product! If there is one feature I would like to see, it's the ability to bulk format elements and label fonts. From what I remember, that was just a tad monotonous.
yWorks employee here, though not working on yEd. Thanks for the kind words.
As for your wish, I think that's already there. You can select many items at once and change them all in the same way, e.g. changing the label font. To select all elements of the same type, simply select one of them (e.g. a label (you may have to use Ctrl+click to select a label on top of a node)) and press Ctrl+A. That should select all labels, while not selecting anything else. From there you can change properties for all of them at once. I think we've added this to yEd Live (the online version) as well recently.
There is also a powerful selection dialog under Tools > Select elements where you can basically select everything that matches certain criteria, such as all nodes with the same color, or predecessors of the currently selected node. Afterwards you can change properties in the panel as usual. This one only exists in the desktop version, though.
Thank you to the creators of yEd - you've put together a wonderful product! If there is one feature I would like to see, it's the ability to bulk format elements and label fonts. From what I remember, that was just a tad monotonous.