I think white grout provides a cleaner, more traditional look. However, both colors work well with the subway tile!

half way in between. i like our pale grey, it gave definition without making me dizzy.

White is fresh...dark looks like a dirty shower wall !

Most of the time I prefer to 'see' the tile itself and not the grout lines, so I like to recommend a light grout for the backsplash. Occasionally, the design itself calls for the grout lines to be prominent, but overall I prefer not to see them.

I like the grout white or a similar tone to the tile in a kitchen.