Some things are the same everywhere, or not very different. Some things, on the other hand, change drastically when you cross a border.
Dinner and lunch don't change. Breakfast does.
Breakfast seems to be the single most diverse meal in the world. Each nation defines itself in its breakfast choice.
In France: ah yes, tourists think it's croissants. Nope. Real French breakfast, at home, is baguette, perhaps toasted, with jam, and coffee in a bowl, not a mug. I think the reason it's in a bowl is that perverse people like my significant other can dunk their bread in it... Littl'uns get drinking chocolate instead of coffee.
In the Netherlands: a massive buffet of ham and cheese. Buttermilk, carefully distinct from ordinary milk in its different coloured bottle. (And a cigar... I don't quite understand the Dutch attitude to smoking, but there you go. And in Friesland, you can add a stiff drink to this, as long as it's after nine o'clock in the morning. Maybe that only happens when they're entertaining foreign business journalists.) But buttermilk, ham and cheese everywhere.
Germany: the cheese and ham are there, with slight differences. But you'll also find a lot of yoghurt and mix-it-yourself muesli - not nice soft easy muesli like Alpen or supermarket mixes, but crunchy tough stuff for Alpine wanderers, with whole hazelnuts, chunks of dried fruit, oats stiff as if each flake has been starched and hung up to dry before putting back in the box. And coffee. Lots.
In Japan: hot rice with a raw egg broken on top, which gradually cooks in the rice as you stir it in. Surprisingly nice.
Spain and Italy: still have to find out whether these countries do breakfast. They do coffee, and you might have a pastry (which my supercilious French alter ego regards as vraiment barbare) to soak up some of the bitterness. But breakfast?
Except in those few places where you can still get churros y chocolate. The doughy, fried strips with their crunchy outside and a scattering of sugar crystals ... those are the real thing, but for some reason the Spanish seem to be turning their backs on them.
Morocco has liquid breakfast; beisara, a rich thick pulse soup. I stopped in the market of Fes-el-Djid for some; in a thick green earthenware bowl with a lump taken out of the rim, and with huge mounds of cumin, paprika and salt on the table for scattering on top. (I like it with a huge amount of cumin and very little salt.)
English fry-up; very rare in my life - but I did just have a superb fry-up at Peterborough Beer Festival (one of the staff perks), hence this post. Bacon and sausages, fried potatoes, baked beans, tomatoes (almost always out of a tin, even for quality breakfasts - a stronger but less acid taste), mushrooms, and hash browns. Ah yes, hash browns - an interloper really, but I do like them.
Russia - I have no idea what the typical Russian breakfast is. But I have happy memories of staying in St Pete's and getting brunch that consisted purely of blinis, sour cream, and five kinds of 'caviare' (actually all non-sturgeon derivation, like lumpfish roe, so not quite as decadent as it sounds).
Best of all? Difficult to choose. That big bowl of beisara comes close. So too does a really crisp buttery croissant and a bowl of cafe au lait, milky and bitter at the same time.
But for me, the best of all is scrambled eggs with smoked salmon, on buttered toast.
PS - for pedants, and others who enjoy great words; Aristology, the study of breakfast (by extension, of fine dining), is featured on an excellent blog, World Wide Words.