Golden Frieza vs Goku Black

Both at their peak of course

Black

Peak Black slaughters Freeza.

Goku and Vegeta were holding their own with FUSED Zamasu in the anime.

And Android #17 all but admitted ToP Freeza is his superior. That means at the least, he's at ToP Goku's even greater anime levels (Before MUI, of course.)

Golden Freeza and SSB Goku stalemated just before the ToP. Beerus/Whis stated their powers were equal.

They did.

I believe both of them were hiding their powers from the other. That's Goku's M.O., and #17 seemed VERY impressed with Freeza despite having fought Goku.

Freeza was enraged. He wasn't implied to have been hiding power from anyone(especially since it was Whis and Beerus who confirmed his power.)

That scene was meant to show us how much Freeza's power had grown since RoF, just from his meditations in Hell. During RoF, he was barely on par with a n00b-SSB Goku. Fast-forward to just before the ToP, and Freeza was now equal to SSB Goku, whose power had increased tremendously thanks to training in the RoSaT for THREE dayS/yearS, in addition to his numerous confirmed zenkais from the U6vs.U7 Tournament + his battles with Zamasu/Black.

Also keep in mind that per the manga, #17 only sparred with SSJ3 Goku... Which makes sense why he would be impressed by Freeza's SSB-level power. /shrug

Black slaughters him.

If Frieza manages to get under Zamasu's skin (like he did with Toppo and Jiren during some moments), thus demoralizing him, he might have a chance. Frieza knows how to play it smart against opponents stronger than him. Otherwise though, Black stomps, probably cuts off Frieza's tail with his ki blade (like Krillen did to 2nd form Frieza but worse), following by impaling him...

Its much more likely Zamasu gets under his skin in my opinion. Figuratively and literally after Black jams his energy blade into him.

I could see Frieza laughing and calling Zamasu a false god or something for having to take over an alternate timeline Goku's body to get the power he has, and then Black loses his cool as Frieza reads him and his movements like a book (in the event Frieza managed to get under his skin), but fair enough. It could happen the other way around too...

The more you mention it the more curious I am to see it...