Compared to textual or topical preaching, expository preaching should be the preferred method for pastors. Granted that some who regularly preach textual or topical are able to proclaim the Word of God effectively.
Count me as one who would rather feast on a regular diet of expository preaching. I say this as one who is a hearer of sermons and not as a preacher of sermons. When I formerly served as a pastor, this was the type of preaching I tried to do.
To provide a definition of expository preaching, I am offering a consolidation of a fuller explanation from Walter Kaiser in his book Recovering the Unity of the Bible: One Continuous Story, Plan, and Purpose (p. 212).
Expository preaching is the method of presenting the Word of God that takes a pericope or teaching block of the biblical text and from that derives both the content and the shape of the message.
This kind of preaching empowered by the Spirit of God will feed the flock. Pastors, give us more of this. Bible study teachers, teach the Word using this method.
Kaiser spells out five advantages of this method (pp. 214-215):
1. Makes it possible for the preacher or teacher to grow continually in his or her understanding of the Word of God.
2. The expositor has to work hard to plow new ground in his or her spiritual development.
3. It saves hours of fussing over what topic to preach the next time.
4. If forces the expositor to face passages that he or she might otherwise have overlooked or deliberately avoided.
5. It yields unusual confidence in the one who stands before God’s people to deliver a message.
See my review of Kaiser’s book.