I've become a big fan of Don Brown. He takes historical figures - often people not-particularly-well-known - and writes good, comprehensive, easy-to-understand picture books on them.
The artwork is simple and distinctive (not overly bright and colorful, though - I find this restful, some people find it boring), and the well-researched books are enlivened by actual quotes by the hero in question.
This one is about a pioneer of the early movies industry and his life. Even if you're not familiar with the subject already, it's interesting and engrossing.