Wicked! Intriguing plot. The book from which it was adapted is one of a number by the same author all giving the (other side) of a well-known story. So a musical with a narrative that you don't know before you see it. Much recommended, although we did see it in its opening run with the lead from the original Broadway production. There have been cast changes since.
Billy Elliot - OK but having seen the film, restricting the story to a stage was limiting, and I didn't find the songs as much fun as listening to Marc Bolan on the soundtrack.
Lion King was excellent as were Les Mis and Phantom.
On the other hand I was offered a trip to London for my 60th birthday and a musical of my choice and have decided to go to see The Mousetrap instead!