who can become god first gon atau Goku

Gon never becomes God simply freaking beast so yea it's Goku. Just because something is made sejak the same person doesn't necessarily make it a ripoff in fact I cannot see the similarities even in the artwork which is good on Togashi-Sensei's part.

Gon is weaker than Killua. He will always be weaker than Killua.

anda also need to specify which Goku. My mind goes to the one from Gensoumaden Saiyuki, who is neither god nor demon, yet both.

ummm its nether of them cause its Black bintang fools

Goku is already a god XD