Aesthetically i usually suggest white grout with white subway to allow the countertop stone to stand out.
Off white subway tile with grey grout.
This pic shows how the white subway tile and gray grout look in both shadowed spaces underneath the upper cabinet and to the left of it and in a more sunny spot close to the countertop.
White floating shelves are mounted beside glass front cabinets positioned over a white and gray quartzite countertop accented with white subway backsplash tile s finished with gray grout in this beautiful white kitchen.
Many people prefer using white grout with white tiles to make the walls look flawless and united.
It makes so beautiful color combination inspired from this image.
However functionally given that it will be susceptible to both grease from the stove and wiping residue when cleaning the top i always offer a light grey as an attractive option.
First off here s a look at the gray grout i chose i went with a light gray option called frost.
But before you name it the best solution for your bathroom thinks about a different approach.