Honestly when I first heard of this anime, it was shown as a "ok" meme gif on Facebook and made me fall in love with the show as well as its main characters. I like how Saitama is this laid back hero but at the same time, does his best to be badass and save the world. I even like his robot companion Genos, he's also likeable too and actually kind of sweet for a tough ass looking hero himself. As well as that, he cares about Saitama and that really stands out with the show!
Love the humour, the characters and its on going storyline. I'm even looking forward to season 2 and hopefully it's good as its original first season!