Some moments that I consider very "cinematic" or epic in Mass Effect (in no particular order) :
Liara becoming the Shadow Broker (and not only is she being a badass in that moment, she's also in leadership mode because she wants UPDATES by the END OF THE DAY!)
Wrex, Bakara and all the krogan looking at the sky of Tuchanka, knowing there is hope for the future of their species
Mordin sacrificing himself, righting his wrongs. I know the usual quotes are on our mind (had to be me/tests on seashells) but I looked at my folder with all my screencaps and look at this one (his face like this with the dialogue wheel option "I'll miss you" is making me so sad):
On a more pleasant note: Mordin singing, giving the performance of a lifetime, and Shepard having no reaction at all which is so funny every time
Mordin having the "sex talk" with Shepard
Archangel is revealed to be Garrus!!!!!!!!!!!
The Reapers first attacking Earth, shit just got very real
The first talk with Sovereign, genuine goosebumps every time
“Are we friend? Or foe?” always been very impressed by Samara's entrance into Shepard's life
Aria's rage and Nyreen's death in the Omega DLC. And in general, the DLC can be really beautiful, look at those colors:
Miranda saying "No deal" and killing her father
The first time you realise you need to look at this flowchart to make sure everyone gets out of the Suicide Mission alive.................
The Suicide Mission itself
Discovering ME1's Citadel for the first time and even going back to it in the next playthroughs, it's such a cool location
Shepard's speeches - especially the one where they say: "The bond that ties us together is something the Reapers will never understand. It’s more powerful than any weapon, stronger than any ship. It can’t be taken or destroyed."
The group picture at the end of the Citadel party
I think the whole of Noveria has an epic vibe to it, I love the old scifi feel and the winter chill we get the entire mission, it's as cinematic as it could be
The Cerberus soldier who has been altered on Mars leading to the conversation between the VS and Shepard, "Is this what they did to you?" - honestly the epicness of their reunion is really something because there's a feeling that the band is back together, but the band is a bit broken at the moment AND the band ponders very good questions, about what Cerberus did exactly and what makes a person a person when they've been reconstructed basically
Speaking of being altered, I think every moment between Shepard, Grunt and Miranda about being designed is epic
Saren going after Shepard on Virmire or the way he explodes at Benezia, he always makes me a bit scared ngl
Javik's first long look at Shepard in the Normandy, something quite powerful in that because he's very impressive and holy shit, that's a Prothean!!!! A living Prothean!!!!
Ash or Kaidan getting hurt on Mars so Liara has to make Shepard understand they have to leave immediately but they're not looking at her so she has to get in their face, it's so funny:
DO YOU GET IT, SHEPARD????? MEDICAL ATTENTION. LEAVING THE SOL SYSTEM!!!!!! NOW!!!!!!
The moment we realize Eva Coré is not quite human and the discovery of EDI's new mobile platform
Wrex facing the Dalatrass
The first conversation with Legion, because my mind was like omfg an actual geth!!!!!!!!!!!!!!!!!!!
Speaking of the geth, being inside the Geth Consensus is such a mindblowing experience
The kid on Earth before the shuttle gets blown up by the Reaper. I know some people don't like him and perhaps he is a figment of Shepard's imagination, but it's very symbolic to what's coming and what worries Shepard
Shepard and Wrex seeing each other again in ME2 and ready to push everyone out of the way to get to the other
Our krogan son is alive!!!!
Admiral Hackett (the man, the legend!) goes to deliver a speech on the Normandy
The fleets arrive. We face our enemy together.
Okay that's a lot already so I'm going to stop, feel free to add to it!