Originally posted by AlbertoJohnAvilBroly would absolutely rape Jiren. Multiple sources state that Broly was the most powerful being the Z fighters had ever faced up to that point. And you also have Freeza fangirling over Broly's power in the lite novel; where he also claimed that baseline SS1 Broly was more powerful than anyone in existence. So if you take Freeza's word at face value, then it implies that SS1 Broly was already beyond Jiren(as Freeza had actually sensed the full extent of Jiren's power as well.)
Actually wonder how'd Broly do against SSB Vegito from Black saga or Jiren
And I'd put Broly above SSB Vegito(from the Zamasu arc) as well, tbh. Broly soaked everything that SSB Gogeta dished out, and just continued becoming more powerful the entire time -- so far as we know, the only attack that would have put Broly down for sure was Gogeta's "full force" Kamehameha. That's important, because SSB Gogeta >>>> SSB Vegito(given that post-ToP Goku/Vegeta >>>> pre-ToP Goku/Vegeta)... So it's logical to assume that a full force Kamehameha from Vegito might not be able to finish Broly.