I voted for Russia. Of the countries listed, I have been to Greece, Switzerland and Russia. From what I have heard, Spain is very similar (though not the same as) Italy. Egypt would be nice, but Morocco already exists - I believe that a difference would be sought after instead of more similarities. That is also why I did not vote for Australia (similarities to U.S., Canada, and U.K.), Ireland (already part of the U.K.), Switzerland (its three mai regions are French, Italian and German in origin) and Spain (see above). I feel that India might be a stretch, considering the treatment that Asia gets in AK (Kali River Rapids, etc.). That leaves us with Russia, Peru and Brazil (of those listed). Personally, I think a South American pavillion would be nice, with representatives of the various countries, including indiginous peoples, but, to choose between the two listed would be tough, especially with that region of the world not represented at all.
This brings me to Russia. The folk history of Russia is quite astounding, as well as their culture. Much of Russia remains a mystery, partly due to the cold war, but also due to the isolationist mentality and the relative isolation of the Russian territory. The pavillion could contain a replica of St. Basil's, at the back end of a square (Red Square), with a "Kremlin wall" on one side separating the space from the next country, and a series of shops (also like Red Square) on the other side. They could put in a restaurant, featuring traditional Russian foods (oddly, crawfish and beer is just as normal in Russia as it is in Louisiana), serve Russian beers and vodka, and have a floor sho with traditional music and dancing. The shops could feature hand carved wood items, matroyshka dolls, and lacquer boxes, among other items.
This is not to say that similar things could not be done with any other country, or that other countries don't have their own unique gifts to share with the world, however, several of the world's larges powers/landmasses/populations are represented, so, I feel Russia should not be left out of the mix.