Regulus Gale winning the tournament was awesome enough, but he goes against all expectations by not only defeating both Peter and Yikzhekel, two duelists who up until then had been utterly Curbstomping their opponents, but also manages to win despite both being Curbstomped at the beggining of the match, and the fact that he had the Lswarm virus poisoning him from the inside out. That kid deserves his victory.
Daniel Clemens becoming the first duellist to take down one of the cultists. With Red Nova Dragon no less.
The entire duel against the Constellar cultist is filled with these moments:
Peter playing possum in order to lure the cultist into a false sense of security and springing a sudden Mirror Force on her to suddenly turn the tables.
Caramon getting his second wind and managing to use Meklord Army of Skiel to finally take down the cultist after spending almost the entire duel as The Load.
The Cultist herself gets one for being able to completely dominate both duellists despite being outnumbered. She even manages to take out Swords of Revealing Light the very instant that it's played. When you can manage to stop them from even attempting a Hope Spot, you know you're a formidable duellist.
On a larger scale, its somewhat poetic that the two duellists to avenge Jacques are his best friend, and the one responsible for his most significant moment of Character Development.
The defeat of all three of Apophis' decks, ending with Art electrocuting and then spearing the Big Bad with a rush of attacks. Then Apophis True Form is defeated by Marduk by the use of Exodia pieces, and with a little unexpected help, the first Big Bad is put away.