Clever "retro" hacks will always gain traction (building a widget out of old vacuum cleaners), anything socio-psychological will usually get traction (dating apps, blog posts about loneliness), anything on advanced math/physics/logic will usually get traction (probably because it makes people feel smart, even though it's not accessible to like 99%), anything tangential to philosophy will get traction (again, makes people feel smart).
I really do miss when HN was a bunch of scrappy entrepreneurs that tried to build stuff. With all that said, it's still the best community left on the internet. At least it tries to abide by the principle of charity, and flame wars/trolling is highly frowned upon. Dang and everyone else does a very admirable job of keeping everyone in line.