first,yes what chikky said that's one of HxH strongest point
2-breaking the cliche paterrn of most manga ,for example the cliche of unloke that villian to fight his boss,etc for example kuroro was kiddnaped wow that was unexpected,let me see tobi or Aizen being kiddnaped yet maintain their badass statu
3-converstions of pure genius
example 1:,here is part of king and komugi converstion
king:what about pitting you arm
komugi: sorry,I only pit my life
wow,did the strongest creature in HxH verse just get owned by a blind fragile girl
example 2:kuroro and kurapica's converstion in the car
kuroro is kidnapped,beaten yet he is the one in control and badass
example 3:king and netero
king:you could only wish to exchange words with me
netero:words ?,smirk do you wish to know your name
those are genius level conversations stuff,you don't see those every day
4-his characterization
they are deep,complex and strong mentally
togashi gives you the feeling that the characters are moving the story not the story moving them
5-use of intelligence and the respect for the reader's mind
6-as for the art,his art isnt the best (yet I think he makes probably the best designs,Hisoka,kuroro,zoldyeks)
but his strongest point is that togashi is a master at conveying the sense of movement,he's the best at that
Togashi of the past took what toriyama started (fighting shonen manga) to the next level by YYh (where naruto and bleact ,etc are currently at) Togashi of the present took it into even more level a delicate,intelligent and mature level ,so right now,Togashi and only togashi give that level,I mean by level that different evolved thing of the preestablished fighting shonen