Alright, so... For some reason, even if Ace's and Whitebeard's death were emotional, Luffy VS Usopp was full of emotions as well etc, i felt more emotion with other moments, such as:
1) Nico Robin's reunion with her mother: with Olvia forcing herself not to reveal herself as Robin's mother but eventually gets overwhelmed by her emotions. I felt it was extremely emotional. I'm not usually crying over what happens in a manga or movie, but i had tears in my eyes during this moment.
2) Rumbar pirates death: the fact that they decided to honor their friend Laboon during their very last moment, is what makes this death very touching.
3) Bellemere's death: how she sacrificed herself to save Nami and Nojiko, refusing to hide the fact that they were her children.
4) Rebecca and Kyros. You can dislike Rebecca all you want, but let's be honest, their story overall was pretty emotional.
So basically, what i nominated/supported. Unfortunately i can only vote for one of them.
I'll go with Robin and Olvia's reunion. That's probably the moment that moved me the most, and it is also one of the least popular choices in that category i think. Deserves at least one vote xD