I'd put off watching Seed and Destiny for years, due to the unbelievable amount of shit talked about them, especially Destiny. But when I finally said fuck it and watched them for myself, I found Seed was decent for the most part, and I actually liked Destiny a lot.
Anyhow, I just got done watching Casshern Sins, and I loved it. I'm a fan of all the 1970s Tatsunoko superhero series, but this wasn't a sequel or even an adaptation. They took everything in a completely different direction and actually might as well have called it something else. But it was very good. And unusual for a cartoon. The entire series was about the characters (and the viewers) coming to terms with the idea of their own death.