For me, the funniest anime series that I've watch is One Punch Man. The characters have different attitude but they all have something in them that makes the anime series funny. Saitama is funniest anime character that I know, he doesn't care about the other things, he just wants to be a hero. In addition to that, his naivety on some things makes him more funny. However, his face is the funniest part of his character, his facial expressions is enough to make anyone laugh out loud.