Good question. So hard to choose just one - John Curry, Stephane Lambiel, Chan, Takahashi, Kozuka, Hanyu...
But if it had to be one it would be Carolina Kostner's winning Long Program from 2012 Worlds in Nice, which I was lucky enough be able to see in person. It was a lovely skate and IMO a fair reward after some near misses and a long and successful career with many ups and downs. After she lands the last jump you can see her smile and relax because she knows she almost certainly has it in the bag, or maybe just because she knows she's done herself justice.
http://www.youtube.com/watch?v=WOf6-8lT9t0