Obviously I'm a big Roger Federer fan.
The big wins from last year (Wimby 2012, vs Nadal at IW etc..) all felt special to me for obvious reasons (breaking records etc...). However, my favorite moment is at the 2009 US Open SF vs Djokovic. Yeah you all get where i'm getting at, the famous tweener between the leg shot that turned into a winner. While many will say it's just a stunt, to me it just goes on to show how much of an amazingly talented shot maker he is. Throughout his career, Roger was always known for his ability to hit winners from sometimes tough positions, that shot was just the tip of the iceberg. The crowd reaction afterwards and even Federer's reaction really made that special, always funny to see the look on Novak's face after that lol. To this day, so many players tried to emulate Roger when they get lobed, but they all fail.