Man... there are so many great moments to choose from in this category. I'd like to read what everyone's personal best moment was in Avengers: Endgame.
For me, the scene where Steve and Tony bury the hatchet and Tony gives the shield back. It was just the way two strong, proud guys would apologize. Call it a "bromance" moment but at that instant, Iron Man and Cap were teammates again.
So many... Tony facing The End, twice. Captain America's appearance at the end, finally at peace with himself and his life. Hawkeye's family vanishing in a seriously chilling scene, and BTW that's the first time anything that guy has ever done that worked for me.
But I really think my favorite scene was meeting Drunk Fat Gamer Thor! No, I'm not kidding. The scene was hilarious but it also had real emotional heft, because Drunk Fat Gamer Thor is a both hilarious and a completely shattered person, his failure to save the universe had broken his heart and his spirit. That's what a really good scene does, make you laugh and weep at the same time, bring out ALL the feelings!