There are so many wonderful children's books available these days and so I am offering these suggestions:
K-3: Chester by Melanie Watt- because it's highly amusing, the illustrations are fantastic, and it's Canadian.
ESL: The Umbrella by Ingrid Shubert- wordless picture book - beautiful illustrations tell the story of a windy day adventure - rich story without words make it a highly accessible book and can be used for multiple purposes - seasons, geographic areas, personal adventure, prediction, etc.
Grade 4-8: The Lightning Thief by Rick Riordan (Percy Jackson series of 5 books) is a highly amusing and engaging action/ adventure series with strong lead characters - both male and female. The Greek mythology provides kids with cultural references used throughout literature.