Is the current flooring staying? If not, what will the new flooring be? If its staying, I'd be looking for a good sized floor mat (washable) that would cover most of the tile as it isn't going to play very nicely with your new choices.

The navy vanity and top look very nice.

In the pictures you've posted, the background of the countertop looks a bit offwhite. If your wall paint is going to abut the vanity back/side splash, then you don't want the white paint colour to clash with the less than white background of the counters. One or the other will look dingy and you don't want that in your nice new bath.

Do you have a sample of the counter? If not, get one and take it to the Benjamin Moore store and get them to colour match the wall paint with the background of the counter.

Another option that would work is choosing a BM white with blue undertones, You can see the difference in this photo below.

A nice new shower curtain, or even better would be a partial glass enclosure for the tub/shower.

Some lovely blue towels and counter accessories, maybe some art for the wall with blues in it would help too.

You have already done all your homework, so it should be smooth sailing from here out.

Have the floor tile professionally cleaned to make it as light and bright as new. Then prime the walls with two coats of white primer to get rid of beige reflections on samples. Then it will be much easier to pick out two or three "finalists". Get Samplize of each to tape up next to the gray shower tile and the navy vanity, move them around, then choose.

What is the flooring please? The original or you changed it?

In northern light, with a plantation shutter, every white is going to be a bit dingy - white needs light, and lots of it to look good.

Please add a photo showing the gray tile with a white piece of paper to help the camera color balance. Open the shutters and take the photo in daytime, please.

BM Chantilly Lace is too stark white for your space.

I'd sample Swiss Coffee. still bright, but won't make your floor look dirty.

The flooring and vanity top look like they're going to fight. One is warm, the other is cool. Maybe White Dove or Swiss Coffee will work. I think you have done all the research you need to do, now you really need to sample. Chantilly Lace became popular during the white on white on white trend, but is unlikely to be the right white for your situation.

Cambria has a BM paint-color-matching tool on their website. I looked for a Cambria color that is similar to your MSI slab.

Here are a few off-whites, based on that:

Chantilly Lace matches with Cambria Hemsworth and Cambria Minnesota Snow

Atrium White (OC-145) and Stonington Gray (HC-170) both match with Cambria Hawksmoore

Ballet White (OC-9) matches with Cambria Ella

Paper White (1590) matches with Inverness Bristol Bay

Cotton Balls (2145-70) matches with MacBeth

I used B.M. Chantilly Lace on my ceilings. I like B.M. Simply White, also, and used it on the exterior trim on my house..

Can you post a photo of the finished bathroom, with all the materials installed, in your light?

I'm assuming that you haven't done any work yet. If you're keeping the floor, I wouldn't use that white counter top--it just doesn't work well at all. But then again gray subway tile in the shower doesn't work either, especially since you're going to see if through the new glass enclosure. Is there ANY chance you can change the flooring while you're at it? If not, can you find a counter top that has both gray and beige in it to bring the two colors together?

Diana Bier Interiors, what would you suggest for the floor tile?

Personally, I would do a pale pale blue or gray ( pull out the vein color in the countertop ) . Whites with those white tops never seem to work out just right.

Get everything installed, then worry about the paint color.

Good luck

Check out Chantilly lace. It’s neutral/no undertone.

If you're going to change the floor, then you have lots of options. You need to narrow down the choices. What style would you want? Do you have any inspiration photos of bathrooms you are drawn to? Do you like small mosaic tiles or large format? Modern/Classic/Traditional/Zen?

and yes, wall paint color comes dead last.

SW Pure White, a clean softer yet still bright white

I chose to not change the flooring in my new to me home so I have charcoal grey/ black large plank porcelain tile in the kitchen and maple golden wood in the adjoining dining room
I chose white oak cabinets in the kitchen with a light white wash, quartz with a warm white ground and golden brown veining and BM Pink Damask for the walls. I liked it so much that I used it in all the areas with the charcoal tile - 3 beds and a den plus the bath with lighter gray tile. Wood floored rooms got BM White Blush, which reads golden white.
It works great, we love it and I couldn’t have found these colors without going through the process outlined above. The flooring drove all these decisions.

If I am reading your post correctly, you have picked a light gray and white floor tile, light gray subway tile for the shower, navy vanity, and white with blue and gray veining countertop. Put all your samples together in the bathroom. Then get some samplize samples of the paint colors that you are considering. Look at the colors at different times of day and night, lights on, shutters open/closed. Also remember, painted walls will be vertical, counter and flooring horizontal. You will know if it works or not.

It seems to me like it will work, but you have to put the samples in your space/room to really know for sure. I have Chantilly Lace in my bathrooms, it is a bright white, and no real undertones. I have a charcoal large format tile flooring, white shower tiles, and blue/gray/green vanity, and a countertop with white with some subtle cool and warm gray swirls, and it looks lovely. I think Chantilly Lace would work for your situation, but you have to consider your lighting, and you have to put the samples all together in that room to know for sure. Oh, you should check the samplize colors next to your window trim and shutters too. Good luck. Post your after pictures.

No white you already have too many whites IMO and IMO the counter and the floor do not work together since are different stylewise. Not choose a color from the floor tile not what and that should be the wall color .