Quality is up to the artist, blender does not create quality, nor does zbrush. They’re both just tools.
Even blender has some tools i find superior to Zbrush. The pinch brush is better imo, and i also prefer how blender scales brushes. But i love the overall interface and customisation that zbrush offers you, as well as the shaders, and incredible polycounts.
Overall i do think zbrush is better, as its made for 1 thing only, while blender is trying to be a jack of all trades, while also being free, but of course you can achieve the same in blender with a couple workarounds.