HxH is a fantastic series. It starts off as deceptively innocent and generic but by the end of the first volume, all of that is proven to be just an illusion.

The series has incredible morally grey antagonists that have their own motivations and existence outside of the plot and they always stay very relevant in the story after their subsequent arc (bar one exception).

The main characters are very unique and each have their own goals and personalities that distinguish them and follow their own journeys. Gon and Killua's chemistry and friendship are also very well written.

The story also has a very considerable amount of depth and realism that mirrors our world and doesn't just limit itself to handing generic "life lessons" to its readers like "don't give up" or "hardwork beats talent" but instead creates very nuanced and realistic situations and explores mature themes, even taboo ones pretty openly and deeply.

The creativity in designs is also astonishing and the art style is very unique.

The fights are very strategic and the power system is brilliant and results in infinite possibilities without leading to escalation.

All in all, Togashi has crafted arguably the best possible shonen series.