donbdense - CDG is high on the list. Sorry, it doesn't feel as busy as some of the others on the list. Maybe it's having two landing runways/3 parallel runways vs. the single arrival runway ops, or intersecting runway configuration, that some of the 'busier' feeling airports are limited to.
World's busiest airports by traffic movements - Wikipedia, the free encyclopedia
Been to 25 out of the top 30. Just short of 19,500 binocular hours with another 1000+ monocular hours. Probably enough to have an opinion.