I have the Subway Ceramics Avalon / Minas with a medium gray grout. And a Shaw's white sink, if anyone is considering that, by the way. (My contractor could have ordered it directly, but at his request, I went through a tile store, and by the time everyone had put their sugar onto it, it was OBSCENELY expensive.) I'm not an installation expert, but at least with the Subway Ceramics, the installers use little plastic spacers between the tiles (I think some others have their own spacers?) when they put them up, they don't do it freehand, so how much grout you get is a function of 1) the limits set by the curvature of the tile and 2) what size spacers they use. So you might be willing to go a little darker with a smaller grout line, or with a handmade tile that refuses to go close together, you might want to stay light. The traditional color is close to concrete. But most modern people don't seem to like that, so do what pleases you!

I have white-white cabinets, white marble and white subway backsplash. I did put a a blue and pewter liner through the splash though. I like a white or light splash -- and I chose glossy tile to reflect the light even though I was adding under-cabinet lighting. If you want to go with either of the two tiles you have in the picture, I like the darker one better. The lighter one looks dingy -- just off on my monitor. The darker one seems more in keeping with the colors in the marble. At least as I am seeing them. I can see it being nice too, especially with good under-counter lighting (I hate baking in a cave, in case you haven't noticed a trend here). Which way to go? Hard to say without the layout and seeing the amount of splash, how it all ties in together and with other spaces -- and without knowing what kind of feel you want. I think that last one is especially important. Look at your inspiration photos and compare them to the space you have and the feel you want -- the look you love. Look for more photos, especially with a color in the splash (I know I've seen a few with various blues or greens in white kitchens). I did the colored pencils and copies of my drawings for several different choices -- they helped me double check my choices, but they were especially important to DH since he couldn't create mental pictures of how things would look together. That really can be helpful.

Just giving my 2018 take on subway tile - I am definitely bored of it, mostly because I see it absolutely everywhere in bathroom and kitchen photos. The bathrooms with subway tile from floor to ceiling are especially puzzling/irritating. Varying width/length mosaic tile has been in fashion for the last several years and there's a lot of variety there - hopefully I won't get bored of that too soon but it can indeed look too busy. My style is a European look with American practicality - simple lines and a luxury look BUT lots of drawers/cabinet space and real wood, no weird stuff like wall-hung toilets, Edison lamps, or old-timey faucets.

We just put up our BS -- 2x4 " white subs -- on Sunday. Not grouted yet but will be gray as the tile on the floor. There is a lot going on in this kitchen and this tile looks best, IMHO. It is a farmhouse; new build. Gray quartzite and leathered black granite CT. I have never liked most BS as it seems to me to be the first thing in a kitchen to date it and distract. The scale of the smaller tile seems good enough here. Just because it is something that has been "done" over and over doesn't mean it's not the best thing for your kitchen. It was what I originally planned for this house going back about 10 years - just now getting the house finished. It's been a four year build :(