Probably not the first one (marble-looking) - I think it'll look weird next to the more artificial pattern of the Cambria (no slight on the quartz - I love the Brittanicca slabs =)

Before deciding though, you really need to have the samples in your space - held up next to your slabs and cabinets - if nothing else, the lights in your space are going to have some effect on the colors.

Have you image-searched for other kitchens to see what they're using with their Brittanicca counters? And have you considered using the quartz as the backsplash?

No to the marble look...too close yet probability of clashing big time. Let your counters be the star.

Karen is right about the marble and the other tiles mimic your cabinets too much....a rectangle within a rectangle.

I like the look of the beveled but wonder about how hard it will be to clean as dust settles over time.

Beveled tile cleans up like all tile. As for grouting it is more work but a good tiler knows how to do it. One thing to keep in mind it installed in subway fashion think about how you will end on the wall with opening. With beveled you have high low but the end will need to be high and have and end piece to cover the cut. The second picture has a metal strip which I think is a good option to end with (they have a name for it as it looks like an “L”). Good luck

Here is a backsplash we did for a client, and the cabinets seem a similar color. Note the color and shape of the backsplash.

Someone a few months ago used these Ann Sacks tile that have a slight raised edge, they also have one that has a slight embossed edge. It was gorgeous in her kitchen. You'd have to get the right white or grey to go with your current pieces but I feel like this might be a choice you could consider. It is a bit more interesting than plain white subway.

There are several different sizes, shapes and colours. The other kitchen, I wish I could find it, hers had a border around the edge of the tile that appears to be a different colour, I think hers were white background with a raised border that was grey. I think it would pull your choices together nicely.

I would go with the bigger size, but in the "plain" tile. You don't want the two patterns competing so close together.