What colors do you already have in other furnishings/areas?

What are we voting on ? I see pics all the same no tile shown. I am not sure tile is the answer for a more traditional look. But the surrounding area is a good place to gather color from if color is what you are asking about. Maybe post the tiles yu have looked at and we can see what you are thinking.

There is nothing to vote on, just extra views of kitchen.

bottom cabinets are stained charcoal and top are bright white (no warmth what so ever). I looked at encore tile in the color celery. I like this color tile. Not sure it will go though.

You are asking about a back splash tile in an unfinished "No warmth" Kitchen? What is not "warm" ? Why celery? What is the counter top? Any "celery" veining? Probably not. It is open to a family room with any warm greens? ? What colors are in that room? Your walls are a gray? Everywhere? What is the temperature of your lighting? Not everyone loves cool led tones......

I would wait until you are entirely finished, go to a dedicated tile store, and bring home samples. This is not a selection you make online. There is no rush. Go to a dedicated tile store. Preferably, you take a sample of your cabinets, with a drawer face;;;;;;;a sample of your white upper cabinets, and even a sample of your quartz tops. You begin there.

playing up the traditional home that I assume you have and refer to...noting the grids in glass window pane and cabinet.....I might try a sample of the square delft style tile. many of the whites in the background and blues can be various tones . as well...some other colors can be mixed in . Warmth can be feel brought about by style ..... not only color. Patterned traditional sq tile w color would suit this more than skinny or any subway tile. Samples brought in will help you finish this up.

I personally love the celery, but it is all about context. If you're buying online, buy a small quantity so you can see them in your house next to your counters and cabinets, in the lighting you have. Also, once you introduce green if you don't have it anywhere else, particularly in the room the kitchen is open to, it will look out of place. If you replaced a very dark kitchen all of the white might look cold to you, but there isn't that much white since your base cabinets are dark, so I think you probably need some time to get used to it. I like your wall color.