Board Thread:Questions and Answers/@comment-26005711-20151226104253/@comment-162.197.92.228-20170612073233

While I'm probably biased and think Hisoka would win (he's my favorite, after all), it doesn't really matter what the statistics are of who is stronger. What matters is what the creator wants to do at the time of the actual fight. For all we know, Togashi might want to kill off Hisoka or Illumi for plot reasons (assuming the fight ends in death, that is). So, it wouldn't matter whose stronger at the moment, as the creator can easily give them some kind of new ability or take something away, making them stronger or weaker.

I still think Hisoka would win, though. From a creator point of view, Illumi's death or loss would greatly impact Killua and the rest of their family (it might even create an arc of the Zodlyck family hunting Hisoka down, and anyone - *cough* Gon *cough* - dragged into the middle of it). However, if Hisoka dies or loses, it doesn't really impact anyone negatively. Most of the characters want him dead, after all.