Maybe it's the floor in the background that is affecting it, but I'm not seeing grays in this tile on my monitor. Seeing earth tones with maybe a slight bit of gray in the swirls. Without seeing the other elements, I would say Quartz or Mushroom.

After a couple of decades of tile floors and faithfully sealing them, kitchen accidents as in dropped eggs and spilled oil, and kids'/cats'/dogs' muddy footprints/barf my advice is that a dark colored grout hides a wide variety of mishaps way better than a light colored grout.

On the lighter end, Light Smoke. On the darker end, New Taupe.

Oyster Gray would be my vote, but with a small grout line, many of them would work well. Some grouts these days come with a sealer in the grout (instead of being applied later) so there are less worries about staining.

Once i picked my tile, the staff at the tile supplier, helped me pick a color for the grout and they suggested the oyster gray. It worked well for us.

Usually we recommend choosing a grout color closely matching the color of the tile/granite. In your case, there seem to be many shades. Bostik Tru Color grout has a super sealer making the grout long lasting with great properties to keep it fresh and clean.