best:
chinese porridge. simple.
japanese medley... soup, rice, maybe pickled veg
or any other asian variant that are warm and savoury... pho, ramen, etc

good:
italian. coffee + cornetto (aka croissant). small, quick.
english baked beans is nice. roasted tomatoes and some eggs, too.
american bacon. american - not english bacon, australian bacon, any sort of german speck, none of that fakon stuff. cured and smoked pork belly strips.
oatmeal.

bad:
"continental breakfast".
in general just a smattering of cold or uncooked stuff. chunks of melon, cheeses and and ham. cup of yogurt and some olives. mehhhh