Alphabet books can be great fun. I usually try to have at least 1-2 out of the library at a time, to work into our daily reading time. And of course, a few are in our permanent collection. Here are some of our favorites.
AlphaOops: The Day Z Went First by Alethea Kontis: what happens when the alphabet is out of order? A fun different way to look at the alphabet. We also love AlphaOops: H is for Halloween.
Alphasaurs and Other Prehistoric Types by Sharon Werner: this book is very clever and amazing. There is a lot of text to appeal to older readers, but the illustrations and dinosaur subject matter appeal to all ages.
The Amazing Action Alphabet by See Hear Do Company: this book is more of a method to teach letters and sounds. We use this when we are doing letter of the day/week activities. But if we read one letter, the kids invariably ask to read more. Learn more about it here.
For even more ideas check out this list of 50 Fantastic Alphabet Books at No Time for Flashcards.