The title says it all: which scene in the show got to the most?
For me, it's the ending of Ep. 9 "ETC". The wife screaming to her dying husband "I NEED TO KNOW HOW HE ATTACKED YOU!" literally scared me, on a level similar to the most intense moments of Fullmetal Alchemist and Evangelion. The utter loss of feeling in her is also powerfully revealing because it's the first time someone is driven into an emotional corner solely because of Little Slugger''s attack on another person, signalling the start of the chain reaction that will eventually engulf the city.