I would do grey. We did small hex tiles and did a light grey and even that showed dirt in front of the sink where most people stand. If you do white it will be grey before long, but not in a good way.

I used Polyblend sanded in Platinum, which is a pale gray. The Mapei grout color Warm Gray is similar and I wish I'd used one of their grouts because I hated the polyblend. I didn't want to deal with keeping white grout clean but wanted something light. I don't have a picture but I'll take one when I get home.

Also, if you use white, you are going to lose a lot of the pattern. It's just going to look like a lot of white. Have you googled for pics?

We have googled pics and a pale gray maybe one shade darker than white is our favorite. Anything too much darker than that is more contrasty than we are looking for. The grout color is very prominent with round tiles. I am concerned that white is too much maintenance, but medium gray is too dark. Perhaps we should provide our own grout.

We used Mapei warm grey and were happy. Like I said, it does get a bit darker in front of the sink, but I can wash it back to the light grey colour. Do you have enough tile that you could mock up a sample board and grout some to see the colours before you commit?

Unfortunately we ordered the tile through the company who is installing it so we don't have access to any tile here to sample with. Fortunately though it's just white tile and white/gray grout so I don't think we can go too wrong.

Use Fusion Pro or Flexcolor CQ as the grout no matter the color.

Please excuse the dirty bathroom floor and camera lens ;)

If I did it again I would use Flexcolor CQ in warm gray. I wish it had been available at the time. (Fusion was but it wasn't available in platinum yet)

The two specific pre-mixed are as stain resistant as you can get. Needs no sealing ever. Color is 100% accurate, no blotching, no fading, no wash out, no mold. Avoid the mastic based pre-mixed grouts that go by other names, even if they are made by the same people.