My selection is "Kubla Khan: the emperor of everything" by Kathleen Krull with illustrations by Robert Byrd.
Krull makes it clear that accurate information and primary sources are few, but despite that lack she creates an interesting look at Genghis Khan's grandson from his youth to his legendary rule as the first Emperor of China's Yuan Dynasty through his later years. Precise details and dates might make this a less than great choice for report writing. However Krull's rich portrait would certainly give older readers a clear feel for the man, his world, and the culture he influenced in countless ways.
Byrd's Chinese inspired art reflect the wealth and scope of Kubla Khan's life with glowing color and intricate detail.