same color as tile or close to it.

The color closest to the background is the best option.

Light would look best in my opinion. Attractive tile pattern :)

Light grout looks cleaner as some homeowners here have complained of grungy look with dark grout.

Grout should match the bacgrond color of the tile so that focus is on the tile design, not on the shape of the tile.

( No need to post the same question three times.)