As I have been re-reading the manga I think that this scene in the manga comes off more intense on Gon's part.
I have always thought that Gon saying this was very telling about how he feels about Killua, but it is the way it is framed in the manga that it gives it more emphasis.
In the anime adaptations Gon's words come off as more casual cause they suit his expressive nature, but it is like the manga makes Gon's declarations of love more special. it is the way they are emphasized that they really come off as if they are meant for Killua and only Killua.
same with this scene
or this
I don't know how to explain it, but it is like the manga does a better job on how Gon feels about Killua in comparison to the anime versions that focus on Killua's reactions instead which seems to reduce the impact of Gon's words.
I kinda have the feeling that the gayer one is Gon in the manga up to the greed island arc lmao. I have always thought that Gon was the one to have developed feelings and the way the manga is written supports it more.
I think Gon being more and more affectionate is what caused Killua's feelings to grow and evolve. At first he became protective of him after Gon retrieved him from the mansion, but the more Gon showed how important and irreplaceable Killua is to him, the more Killua's feelings grew. I feel the manga does a better job at showing why Killua feels so strongly towards Gon, it's because Gon have felt strongly towards him all this time.
