A Tech song to show off, in my opinion, has to be one with a killer verse AND a killer beat. You can't get someone to listen to somethin without gettin your foot in the door first, and that won't really happen with the average person without somethin catchy.
Songs that come to mind for me are Who You Came To See, My World, Get The Fuck Outta Here, Like Yeah, T9X, Twisted (for the old school heads), Killer, The Industry Is Punks, Midwest Choppers, Fan or Foe, and Paint A Dark Picture.
I'd pick any one of those. But choosing JUST one, it would have to be...Paint A Dark Picture. That shit is just all kinds of crazy.