I don't have a favorite book in the Bible. But I do like the book of Revelation because it foretells what the world will experience during the time of God's wrath and how to prepare the church for the next chapter on God's timeline chart. But I do like the book of Romans also. This is a great book when witnessing to people about Christ. If gives the basics for the new Christian.
If anyone reads through the entire Bible (some do in twelve months), then they will read more Old Testament than New Testament. The Old Testament is longer than the New, so obviously they will read more OT!