I've been to the Louvre, Prado, National Gallery, ...

I've been to the Louvre, Prado, National Gallery, Tate, Guggenheim, Metropolitan, MOMA, Stedelijek, Rijksmuseum, Philadelphia Museum of Art, Denver Art Museum, Art Institute of Chicago, and more and still rate The Museum of American Visionary Arts as one of my favorites. Viewing and interacting with artwork by untrained people who are/were socially and culturally out of the mainstream and art world is a wonderful treat. And visit the gift shop which is another fun experience.