Cahill's goal in the group stage was one of the best in the entire World Cup, hands down, and it came out of nowhere too. I think he even said that it was the best goal he has ever scored in his entire career.
The primary reason last night's goal was better though, at least in my eyes, was because it happened in the World Cup final. Not only that, it also happened late in extra time in a scoreless and defensive-focused game, it was scored by a substitute player (first time in a WC final), and it was the goal that allowed a Euro team to win in the Americas (first time in history). The cross from Schurrle that set up Goetze's two touch goal was damn near perfect too.