[Lumen]

Never liked Saitama, he was even poorly portrayed in the anime than the manga. That being said, the funniest character in One Punch Man has to be King.

The deadpan attitude of Saitama killed me he was hilarious although clearly he had a lack of personality, I never found King that interesting to be honest.

The thing about Saitama is that he is so painfully annoying because his character is made to be funny, it is pushed into your face constantly. The jokes got old the second time, the millionth time it was just annoying. Saitama is meant to be a joke. (Hence why he isn't funny in the long run.)