same color as the tile. The tile will still show pattern and texture.

too bad you didn't dry fit, so you wouldn't have the small pieces left.

I don't like "grids" so I would match the color of the tile, but some people like seeing the grout lines and go darker.

There is no wrong or right answer!

Definitely not black, too harsh. What color are your counters, light gray?

I dislkke white grout anyway so d a nice gray .and BTW the dry fit would not have helped except you could have done the samll pieces in the corner . I am trying to figure why all that grout with small tiles .

Oh, your such a black and white thinker! Sorry, I had to say it. What about all of the shades of grey inbetween?

light gray works very well with white tiles

I’d go with a gray, just dark enough to not show dirt or be a hassle to keep clean and bright. There will be some contrast with the tile, enough to create a clear grid pattern. If you go to the trouble to use thin vertical tile, you want to celebrate the grid that you’ve gone to all that effort to set! So, anything from a dove gray to a medium gray would be my choice.

Mapei Cobblestone is just dark enough to show a mild outline, without turning it into graph paper. Use the Ultracolorplus FA or Flexcolor CQ single component grout. Alabaster is about the same light/dark value, but a bit on the warmer greige side.

I see no one judging here

White.

People are NOT judging. They are providing an opinion. It's your decision.

Light gray should accomplish the look you want.