Something fast but complete. When there's more time you can sit down and prepare something more elaborate like some scrambled eggs, but if you're in a hurry you can always carry with you a protein bar.
Depends on what you have available but from what I heard, a nice smoothie, or eggs could be a good option.
If by "travel often" you mean unable to sit down for anything then I think power bars or protein bars could be a very good fast and easy alternative.
I say a breakfast bar for me even tho I don’t work when I go to school I would bring a protein bar or breakfast bar to help me with breakfast
I think a great breakfast to have when you travel a lot might be eggs, toast, oatmeal, or maybe even a protein shake. These things can be eaten fast and also have health benefits.