like what you have done!! It's a straightforward, closed galley kitchen. So I would place some ?Italian or Moroccan ? style colorful patterned tiles. The interest and color provided will be a plus, and because the space is closed, it will not conflict with whatever else you have going in dining or living areas adjacent. You have enough of a stretch, to make the impact worth the bit of extra cost, and this will NOT overwhelm your space. Bring home a sample of a colorful patterned hand made tile and and see what happens !!! More into neutrals?? well, there would be many if that's your choice. Just have to bring samples in , either way.

How many different gray and white tiles did you try? Why didn't they work?

This quartz is too busy to add a patterned tile. A crackle would be your best bet to give some variation between tiles without adding a strong pattern.

Here's an option that will work for sure with all the colors. It will also let light bounce back. This was the first tuxedo kitchen that I fell in love with!

I love everytime Mayflowers posts that tile. It's amazing. I totally agree that crackle tile would look great.

do you have lg rococo? don't see a Rocco.....unless it's a new one. Anyway, still seems a plain counter.

It's darling so far!

Can you wait until your counters are in to choose your backsplash? I was tryjng to imagine how white wasn't working but trying to decide on "the" white with only that small countertop sample to check against can't be easy.

I also like the defined edge grey crackle mayflowers and mark_rachel posted. Scrolling through Houzz kitchen photos that featured LG Rococo counters, whites and greys were pretty prominent. For example (although this turned out to be a Silestone Lyra counter. I noticed the cabinets colors):

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If you want to post some samples, we can weigh in if that would help. But colorwise, you sound like you're in the ballpark and just need to keep trying until you find the shade you like.

I was thinking of the Crackle as well.

The photos I saw of LG Rococo were heavily veined, so I don't think a
pattern will work, though I would like to see a different shape than
subway because that kitchen has a lot of same-sized rectangles.