Noah and the Ark by Kelly Pulley is great for beginning readers. I tend to like picture books better than easy readers because the illustrations are prettier. The next two books have wonderful, large illustrations: Two by Two by John Winch and Noah's Ark by Jerry Pinkney.
A Rainbow of My Own is always a favorite. "The rainbow is his friend," Bobo, age 3.
Elmer is a rainbow elephant. We also read Elmer and the Rainbow. These are fun to share one on one because there is so much text. The colorful illustrations still hold his interest, so I can get through the whole story. He asks lots of questions, too.