My favorite Psalm is also the shortest Psalm and it is the shortest chapter in the entire bible. What makes it so appealing to me is that it packs so much theological punch into so little actual space. My favorite Psalm is Psalm 117:
Praise the Lord, all nations!
Extol Him, all peoples!
For great is his steadfast love toward us,
and the faithfulness of the LORD endures forever
Praise the LORD!
I found a great little summary of this Psalm in Kingdom through Covenant by Peter Gentry & Stephen Wellum. Here is what they have to say:
This is the briefest and shortest hymn in the whole of Israel’s Songbook (Psalms). According to the format standard for a hymn, there is a call to praise Yahweh, followed by the reason for praise. In Psalm 117, verse 1 is the Call to Praise and verse 2 the Reason for Praise. In the section giving the reason for praise the word pair hesed [steadfast love] and emet [faithfulness] is split over parallel lines. Thus the reason for boasting about the Lord is his faithful loyal love in his covenant with this people Israel. In fact, the celebration of this quality summarises the entire Psalter. When a budding scholars completes a doctoral dissertation, the dissertation must be summarised in three hundred words. This is called a dissertation abstract. And Psalm 117 is the dissertation abstract for the entire book of Psalms. It summarises in just a few words all the Laments, Hymns, and Songs of Thanksgiving in Israel’s hymnal, including the enormously long Psalm 119. The Lord is worthy of the worship of his people Israel because he demonstrates faithful loyal love in the covenant relationship. (pg. 145)