people say because he's one punch man hell kill goku in one punch. I disagree
Soooo some issues with this match up is Saitama goes from 0-100 in a matter of a second where as Goku in terms is a god but he takes a while to warm up. Plus we have not seen Saitamas full strength quite yet from the anime so it's really hard to say. Also Saitama defeated Freezers "equivalent" In his universe in just a couple of punches. But all in all I believe it would be the most epic battle of all time.
I honestly think Saitama can go toe to toe with Goku (Goku when he first fought Vegeta), but if you want an all out battle, then current SSGSS Goku easily kills him with One Punch 😂 I don't think Saitama can match his strength with Beerus to punch the universe to destruction like Goku did against Beerus.