stomach wise, since luffy's can stretch more than an average person, he can eat the most ramen... but allen walker from d.gray man can eat so much... everytime he order... its like he's ordering for a big party or he hadnt eaten in months or something
I think choji or naruto.(choji:he can use his jutsu to stretch his mouth & stomach)
(Naruto:Uses his shadow clone jutsu to eat all of the other ramen before luffy or goku.)