The two best scenes for me are the confrontation between Hulk and Loki. Loki trying to "impress" Hulk with his god statue, then Hulk took him bu the feet and completely slaughter him, finishing by the "puny god" line.
The second was the Loki escape, trapping Thor in the shield cell "When will you learn how not to fall into this trap", or something like that. It was such a good summary of the Thor / Loki relationship and personality.
Tom was absolutely brillant in both scene, expecially in the Hulk one where you can feel the fear under the pseudo god confidence.
But, yes there were so many other good scenes. The video game one with Tony, the coulson death, Tony saving the world, then being "awaken" by Hulk, Hulk randomly punching Thor after they both defeated their enemies, the appearance of Thanos, and his strange and frightening smile when he pronounced the name "Death", Thor first appearance (BW, cap and Tony are on a plane, taking Loki to Fury. Then Flashes appeared out of nowhere around the plane and Loki tell something like "Bad news, guys")