Charleston has been ranked once again by Travel + Leisure readers as the number one U.S. city for the seventh year in a row. Charleston ranked 12th on the magazine’s list of 15 best cities in the world, one of just two U.S. cities to make the “World’s Best” award list. Furthermore, Charleston ranked at 10th last year and #1  in 2016 on the world rankings list.  The magazine’s editor-in-chief, Jacqui Gifford said of Charleston’s showing, “it’s been exciting to…