#2 Emery's tactical superiority
Pochettino is in some ways rightly lauded by the media, fans, and pundits alike. He's taken Tottenham, a club that hasn't achieved highly in PL history, to Premier League contenders and Champions League regulars.
Emery, however, got the better of "Poch" today, and essentially "out-tacticted" him. The game plan was apparent from the off, in that Arsenal pressed Spurs and denied them time on the ball. This made them nervy and culminated in taking the lead via Aubameyang's penalty.
Tottenham did get into the game somewhat after 20 minutes and did get 2-1 in front, but this was in part due to Arsenal's defensive lapses as much as it was Spurs performing right tactically.
Both managers changed formations in the second half, but Emery's alterations proved more telling since the introductions of Ramsey and Lacazette were too much for Spurs' defence to handle.
Emery clearly did what he could to win the game, and was bolder and utilized more initiative than Pochettino to win this specific North London Derby.