The credits list seven writers: Brianne Battye, John Dombrow, Chris Hepler, Cathleen Rootsaert, Mac Walters, Jay Watamaniuk, and Patrick Weekes. They are listed in alphabetical order, not in an order of rank/seniority/contribution.
In all seven cases, these writers have worked on various Bioware games. It seems a little obvious in hindsight, but the best place to find similar writing would be the same studio, i.e. the Dragon Age series.
Source: http://www.mobygames.com/game/windows/mass-effect-3-citadel/credits, but if anyone asks I watched through the end credits myself.