Nayr's Core5000 deck (Frequency Dictionary of Japanese)

I second this. Great deck, a very relevant alternative to the regular core decks. Not as beginner friendly perhaps, but it doesn't feel outdated at all. I've been using it for about a week now, and I just ditched the regular core deck even though I was already pretty far in - I just got really tired of 80's style textbookish "business" Japanese.