Dragon Ball, no doubt. Probably followed by something like Fist of the North Star. in my country, doraemon is first, naruto is second but actually, i hate naruto the most populer manga in japan is one piece in north america is naruto.the top 5 manga seris right now are in order one piece naruto bleach full metal alchemist and fairy tail dragonball z , but in japan it is indeed doraemon , naruto and one piece , it's just that europe don't have much anime except dragonball z