More time in Shinjuku or Akihabara?

During an upcoming trip to Japan, I currently have an extra day to fill while i’ll be in Tokyo. I already have a full day in Shinjuku and another full day in Akihabara on my itinerary. I’m quite into Otaku culture and from the research I’ve done Akihabara is the place to be for someone with my interests but Shinjuku seems to be much larger and also offer some Otaku attractions but with more emphasis on nightlife. If i’m not too interested in a Vegas-like experience (casinos, hostess clubs, bars) would it be smarter for me to spend my a second day in Akihabara or in Shinjuku?