The Menswear Staple Face-Off

Quick question, what makes a guy's outfit pop, what's the one piece that every man should have? Is it something that can move between formal and casual with ease? Or would it be the statement piece, the signature of any man, that announces his arrival and cements his impression?

Here's the first face off, between the Desert Boot and the Denim Shirt. Which would you deem ESSENTIAL?

Menswear Essential: Denim Shirt or Desert Boot?