Zoro cutting Pica was great, because he was a strong opponent, one of the strongest from dofla family; full haki and mountain size....Zoro cutting a cliff is normal for me.
Comparing to law cutting the lab/mountain in PH was maybe all DF but still, he did it. One cannot diminuish law's mastery over his DF to overhype zoro's strenght, that's literally diminuing zoro's true value...
Zoro without sword wouldnt have cut pica or a cliff; law wouldnt have cut the lab/mountain in PH without his DF, and that's it.
Law cut the lab/mountain with no Haki, even if its all DF its impressive to me; Zoro cutting a cliff....meh, not that hype everyone's making...