@Beth H. 🙏

Have her contractor do a mock up board with the colors she is leaning towards. Personally, I'd stay away from the dark grout. That's a great grout product.

I'd go with a very light grey, much lighter than any of the three posted.

From my own experience there’s nothing better than a sample board in helping one decide. My contractor made 3 for me, one each for the three grout colors I had narrowed my choices to. As I recall he left them for me on a Friday so I had the whole weekend to think it over, get input from family, see the samples in different light, etc. It was a huge help. Good luck!

If her counters came out darker than she wanted, the last thing she should do is pick a dark grout! I personally detest dark grout with white tile. It always looks too busy to me. If I were her, I would select white grout and add lighting under her upper cabinets. I chose off-white subway tile and off-white grout 11 years ago when I remodeled my kitchen. I've never had an issue keeping it clean, even with a six burner, frequently used 48" gas stove. Subway tile has been in use since 1904 for those of you that consider it a "trend".

No dark grout, even the light ones let the shape of the tile stand out. I have white tile with a very light gray grout, very glad that I didn't go with white grout, but also glad that I didn't choose anything darker. Let the tile shine, not the grout lines.

In your close up picture, see how the light grayish wall color comes through the mesh of the tile - do that color. It will be bold enough. Just look how the tile looks in the further away picture.

Some inspiration:

Good luck!

I would not use a dark grout, the tile seems a little busy as a result of the shapes. I love the tile. I would go with a light, light grout. However some may like the dramatic look. I recently did 3 x 6 bright white subway tile with an Artic White Grout, so happy I did not do a darker grout. Turned out beautiful.