I have to admit, I've only played the Citadel DLC with a character who (sort of intentionally) got ALL of the Cerberus personnel on the Normandy killed in ME2. Yes, even Jacob and Miranda. Yes, I made sure to put off the suicide mission long enough to watch Kelly Chambers get chopped into smoothie, just so I could take Legion to Tali's trial and watch the Quarians shit bricks.
I almost feel like I'm not really missing anything, but now I'm curious...
Just finished it... that was some damn fine DLC. I haven't had that much fun in a while. Nearly every moment was perfect. Some touching moments, many hilarious ones.
My favorite by far:
Shepard: Glyph, did you find the target yet?
Glyph: He is accessing a secured archive. He does not wish to be disturbed.
Glyph: I thought he was you.
Shepard: Argh! Find him again!
Jaavik: Stupid machine...
Close tie for second place:
"I don't wanna talk about it!!!"