NYTMARE'S TOP FIVE FAVORITE SOCIAL DEDUCTION BOARD GAMES
The Resistance / Avalon - This is my top pick due to the amount of complexity and depth of play it manages to squeeze in with the fewest number of rules. All of the joy and sorrow of Werewolf or Mafia without having to have one player sit out as the GM or making people sit and wait around for the game to end once they're killed.
Two Rooms and a Boom - It's like two simultaneous games of Resistance being run at the same time in two different room. The game is played over 5 rounds between two(ish) equal(ish) teams. The red team wins if they manage to end the game with the President in the same room as the Mad Bomber, and the blue team wins if they manage to keep them separate and the President safe.
Dark Moon - Originally created as a slimmed down fan version of Battlestar Galactica, it became so popular that the creators re-themed it published it as it's own game. Now it's a sci-fi "trying to identify the infected players while not being killed, while escaping a moon base, all while The Company is trying to back stab you and get an infected player back to Earth."
Dead of Winter - Probably my pick for the best RPG experience packed into a board game. This is your typical "zombie story where the zombies are secondary to the human drama" kinda thing. Mostly co-op, though everyone is also trying to accomplish their own secondary selfish goals which might conflict with the greater good, AND it has the added benefit that someone out there might be a traitorous jerk trying to ruin it for everyone else so that they can win.
Deception: Murder in Hong Kong - I think that the best description I've heard for this one is "Dixit, but with words and also a murder." One player is the Forensic Scientist, describing the details of a murder investigation to the other investigators, but the only way they're able to communicate is by choosing words off of randomly selected list of clues "The Location of the Crime: A Vacation Home, A Park, The Supermarket, A School, The Woods, A Bank." The rest of the players are all investigators with the twist that one of them is also the murderer, trying to throw the other detectives off their trail while incriminating someone else