I'm a little surprised that the Hermitage failed to make the list but I guess St Petersburg can't compete with Washington, Paris, London and New York in terms of tourist numbers. I'm also disappointed that the entry for Seoul is not the KimChi Museum.
Best museums I've been to not on here include that one and the Hermitage, the Egyptian Museum in Cairo, the Holocaust Museum in DC, the Holocaust Museum in Tel Aviv, the Vasa Museum in Stockholm, the Hong Kong Museum of History, the Acropolis Museum in Athens, Topkapi Palace in Istanbul, the Spy Museum in DC, the Newseum in DC, Udvar-Hazy in Virginia, the Cloisters in New York, and maybe the Van Gogh in Amsterdam
oh... also.. the Kuntskamera in St Petersburg, and the Space Museum in Moscow, and the War Remnants Museum in Ho Chi Minh, and the American History Museum in DC, and the Ethnographic Museum in Addis Ababa, and of course Versailles, and the Hagia Sofia... I've been to a lot of museums. :P