I believe it was camp forlorn hope where I set C4 EVERYWHERE to ensure no man would live from the explosion.
Using a stealth boy, I snuck around the camp and placed the bombs, (They would shoot me on site if I came out from hiding.)
I had First Person Cinematic mode on, and well, I jumped off the cliff, in 3rd person, clicked R1, and in slow-mo, the camp lit on fire, with me jumping out of the way. Really wish I had a PC to take a photo of that one moment. The bodies flying into the air, the explosions red and orange hues behind me as I leaped off the cliff.
Very Beautiful moment of Destruction.
How Could I have forgotten my favorite moment?
Charging up Black Mountain at night, fighting the Super Mutant Infestation.
Though, this is probably what everyone experienced, mine was unique for me, and has only happened once.
5 Super Mutant masters perched themselves ontop of a hill, with incinerators, while some on left side were firing at me as well. It was like an epic war scene... thousands of fire balls raining down upon Cass and I as we run for our lives.