I noticed that the quartz textures differ between the 128 and 256 pixel versions (I did not test the other resolutions). In 128, normal quartz looks similar to the default MC texture in that there are grooves between the individual blocks. Only if the quartz is smoothed, these grooves disappear. But in 256, no grooves are visible between connected blocks on normal quartz. While this looks nice, I don't think it's supposed to be that way, as it's different in 128 (and default MC). Also, I would recommend to keep the general appearance consistent with the default MC texture for visual compatibility.
Smooth quartz, on the other hand, has no grooves (which makes sense and is compatible with default MC), but it has a more prominent, darker surface pattern that actually looks less smooth than normal quartz. I would highly recommend to use the same (or an even smoother) appearance on smooth quartz as on normal quartz.
Currently, as there are no concrete stairs and slabs available in Minecraft, smooth quartz is the only material that allows us to build reasonably complex, plain white buildings (mixing white concrete blocks and quartz stairs/slabs is not optimal, because the base color is different). That's another reason why I would prefer a very smooth, almost plain white texture on smooth quartz.
Best regards,
Joerg
