The most emotional moment of the Mass Effect Trilogy?

Tuchanka on ME3. Everything about that quest line is so emotional... well, assuming you have Mordin and Wrex alive. I get chills about Eve's speech, I feel deeply touched when Wrex announces how the name Shepard will mean Hero, I always tear up when Mordin sacrifices himself (shit, I'm almost tearing up even now thinking about it). In fact, I find the Mordin scene to be the most emotional out of all (though Mordin being my favorite character might have something to do with it). There's other great tear jerkers like Thane's death but to me Mordin's scene takes the crown because of how it links to his whole character arc. I found it especially emotional when playing as Renegade Shep who confronts how his views on genophage have changed and Mordin actually yells "I made a mistake!" (btw none of my Shepards have been able to shoot him in the back, one actually raised his gun but was unable to pull the trigger).

I must give a special mention to the music they use on Tuchanka. It's a major reason why these scenes are so effective. 

Not THE most emotional, but definitely very emotional (at least for me): the mission within the Geth consensus.

Shepard's first contact with the Geth painted them as ruthless killer machines who impaled humans on spikes. Sorta like an alien Terminator army with intranet service. Then along comes ME2 and we become acquainted with one of their kind. Our view of the geth then changes a little and we see they're not the bogeymen from ME1. But then ME3 comes out and our minds are blown. For the first time, we get to witness the Geth/Quarian conflict from the Geth's perspective, something we never imagined would be possible. We learn about Legion's origin, how he witnessed the genocide against his people, what happened during the Morning War and what truly drove the Quarians away from their home. To learn their exile was self-imposed because they became afraid of their own creation and how anguished Legion must've been for almost over three centuries - 300 years!!! - just because he gained intelligence (as was expected from any AI) was mind blowing. And to see this revelation end with the same question that started it all followed by Legion's self-sacrifice was heart wrenching.

Does this unit have a soul?



Afterthought: The Quarian/Geth conflict is one of my favourites because IMO it foreshadows one of mankind's possible futures when we finally develop advanced AIs. Being driven away from Earth and having to wear astronaut suits whenever we visit a colony or alien civilization might one day become a reality.