The Witcher 3 has like actual writing and character drama instead of the typical Fromsoft "what if we just, like, implied that there was a story and let players use their imagination to fill in all the fiddly bits like what it actually is?" style of Bloodborne.

Bloodborne has what is ostensibly very good actual gameplay but I wouldn't know because it was a console only game so I just have to use DS2, Sekiro, and DS3 as points of reference there to infer what it was actually like, whereas the Witcher 3 has very janky and not very good mechanical gameplay although to its credit it is the least bad of the Witcher games in that regard.

Conclusion: they're so radically different and each clearly win in the areas that are their individual strong points that I don't know why one would even compare them. It'd be like comparing Armored Core 6 and Rogue Trader and asking which was the best game of 2023.