1) Saitama. because he is genuinely good and the few actual heroes that wants to be a hero. Unmotivated as he is, he's probably saved the earth a few times and isn't bothered with getting fame/riches.
2) Bang. He's seen enough of the world to know true power and is again does what he does because he knows he can make some differences. Also never boasts about his power /rankings.
3) Darkshine. Similar to Bang and I know he has been holding back with his powers. Also cause he has that 'innocent' look, I wonder how much power he is with holding if he has been going through a S-Class life so nonchalantly.
4) Genos. Pretty self explanatory, selfless, doesn't give up, cool aside from being a little dumb he's he perfect sidekick. He has so much utility and fends off small-frys for Saitama.
5) King. I know some hilarious shit is about to go down every time he appears.