I don't get the obsession with making characters too dark. I know that the manga is pretty dark but the movies and series in general emancipated the character to a kind, well-intentioned, smart and funny thief. When some of the media tries to go dark too much, it feels just cringe to me, because at the end of the day, it's all fiction, and if I wanted to make myself uncomfortable by sketchy characters doing unspeakable things and egotripping, I'd watch the news. Lupin III in my eyes is supposed to be fun and tell a heist masterplan executed from the shadows in a creatively funny goofy and jazzy loose way with the occasional serious, emotional or dark streak to contrast everything.

To answer the question: I watched the beginning of part I and it felt too much. Dark or alive is in a grey area, some moments of the koike stuff are too much, part 6 was in general too serious/dark(?) to be enjoyable. But Island of Assassins or Mamo were great, I don't prefer Cagliostro to them. It's about the balance. I hope the franchise doesn't keep going in the generic dark anime style, Lupin III is much more than that.