It's hard to compare something as being the Hacker News of "X", but one forum that has been filled with pretty solid discussion is https://bitcointalk.org/. Contrary to its name it also holds discussions on other crypto topics in the 'Altcoin Discussion' section.
👤 rvz
All the cool kids, moon boys and the crypto hype squads are screaming in here: [0]
If you hate cryptocurrencies or crypto maximalists, beware.