I realize this is a subjective statement, but it is true nonetheless. Because of this, I enjoyed reading Leon Morris' classic entitled The Atonement: Its Meaning and Significance.
This book is straightforward and to the point. The book is composed of eight chapters, each of which deals with a specific aspect of the atonement. The topics he covers are: covenant, sacrifice, the Day of Atonement, the Passover, redemption, reconciliation, propitiation, and justification.
I appreciate this text for two reasons. First, Morris spends a good deal of time looking in the Old Testament to show how Jesus has fulfilled what was prophesied there. Second, Morris sticks to the literal interpretation of the biblical text. In doing this, he shows how liberal theology fails to read the bible for what it says.
If you like to read about the atonement, you'll enjoy this one.