Anime Zamasu stops at SSjB Vegetto, stomps all of his lower forms.
Manga Zamasu could honestly be anywhere between SSj3 Vegetto and SSjB Vegetto and it wouldn't change anything. Vegetto was complete overkill considering he's on par with Beerus, who still has not been surpassed yet power-wise (and is debatable even in the anime to an extent), who was shown to be able to one-shot the Complete Super Saiyan Blues once he got just a little bit serious.