Our cabinets are paintet BM Gardenia, a very warm white.
Our backsplash is Daltile black & white 3x6 subways. The white is what Daltile calls Arctic White. It's the brightest white they make.
Here's a shot.

We think they go well together.
While not always possible, it's best to look at your tile and cabinet colors at different times of the day and under the light that will ulimately be in your kitchen.

We are putting in a more period kitchen for our 1918 four square. We had white (ok, not sure the name of the shade of white, but it's not white white) and black hex put onto sink countertop and will have biscuit subway w/black pencil liner put onto backsplash. . It was a closer match to the hex tile we added (not exact, but close enough). Our Kohler sink is white and the stove and diswahser (just what we already had, not new purchases) are white). We don't have the biscuit subway tile up yet, but the hex, which is not a white white looks fine, even against the white sink. Besides picking biscuit to more closely match the hex, we thought it looked better w/the painted yellow cabinets we had put in. However, I think either white or biscuit would've worked.

I found that "white" subway tiles vary greatly from brand to brand. We have white cabinets (a soft white but still crisp) and went with a slightly less white subway (gloss white from Lowes). I felt that going slightly darker than the cabinets warmed up the kitchen a bit. The whiter white tiles (from The Tile Shop) were whiter than my cabs and just too white.
Here's a picture:

I don't have white but a lite cream colored subway. I think you need to get samples and view them over a few days during different lighting scenes (sunny, cloudy, night, daytime with lights, etc.) Every place will have multiple white tiles but the white color can be very different. For me I went thru 20+ tiles sitting on my counter for over a week. Some looked better in a particular light. I finally went with the one that looked the best during sunlit days. I kept a tally and asked everyone who walked into my house their opinion and why.

I looked at Daltile but ended up with Crossville Savoy. You probably see a lot of Daltile and American Olean subways because they are the standard, flat, straight cut, classic, clean subway adn they are available everywhere at a very reasonable price. I don't have a lot of splash, and the installation was the same either way, so it wasn't a big splurge, but I liked the thicker, slightly irregular look on mine. Either is good, and neither white would be an exact match -- they just have to have the right tones to go together. If you use a gloss tile, it is already going to look different because of the shine -- and that's not a bad thing. I wanted the gloss to reflect light under my cabinets and to be different from my cabinet finish.

Floridatile retroclassic flair makes a great tile. They are handmade looking. the glazes have a bit of variation, if you go with a color, which I love for a really antique look. They even come in green. Under $5psf.

I think different whites can work well together, and it actually give a bit more depth when things don't match, exactly.

A famous designer (I wish I could remember who) used seven different whites on the millwork in his main rooms and it all reads as "white". He says it gives added dimension and does not look like a series of different colors.

If anyone has found a white subway with some texture and interest, that looks handmade, but allows for tight grout lines I'd love to hear about it. It seems a trade off between machine made/narrow grout lines and hand made/wide grout lines.

I used white Daltile 3x6 subways in my bathroom walls. The floor is matte hex in the only white offered at that time, which truly is an off-whitish color. WIth a white toilet and sink and a white cabinet sitting directly on it, it looks fine.

I again used the Daltile white subways on my kitchen walls near my built in fridge, which is paneled to look like my cabs. That white matches the white 4x8 beveled subways I am using on my kitchen backsplash. I am sure if you look up close there will be a difference, albeit very slight. I have off white cabinets (BM's Man on the Moon) which are almost to the yellow tones. My appliances are white, and the combination of the subways and appliances look nice together (even tho there are quite a few 'white appliance nay-sayers' out there!).

I think the combination is very crisp yet softens the typical all white look. I don't like harsh kitchens, and find too much white and stainless appliances tend to look sterile and harsh. Perhaps working in a hospital for too many years has me swayed that way.......

Horus -Broadway 1 series in Latte is a reasonable white tile with a hand-made feel.
Crossville's Tuscan Clay in "Bianco" works well with washed cabinets.
Subway Ceramics makes a beautiful dry-press 3x6, but it's not cheap.
Lanka Tile and Metro Tile are also both pretty reasonable, though only the Lanka Tile has a variety of trim available and even those are limited to surface bullnose.
Ann Sacks has two affordable lines in their Ceramic Basics category; Ann Sacks NOW and Capriccio.

I try to advise my clients to avoid the Daltile and American Olean products for their residential projects. The quality control is spectacularly bad for both, with pinholes and scalloped edges in the glaze becoming a common "feature" instead of an anomaly. If you absolutely have to use the Rittenhouse for some reason, look at the Precision H2O Tribute series of moldings to dress it up at an affordable price. Precision H2O is licensed by Daltile to reproduce all of their glazes, including the Kohler colors.
Best of luck,

Thanks for all the feedback and pictures - they helped! I was able to pull my available samples and look at them all, and see the whites do vary a bit!

I have Subway Ceramic sample - it is beautiful, was planning on spending the money as a splurge.. but doing 4 baths, and all the showers, shower pans, and everything else we are doing, it became to overwhelming to try and figure out all the small details, so I've enlisted the help of a tile store , and as someone mentioned, Daltile is reasonable and very available! However, that said.. I may just wait a while on the backsplash!

Tileshop.com has one that's priced pretty well. It's their Oxford 2x6 and it has a wavy handmade appearance.

Lisa, look at the Crossville Savoy. It's surface is a bit wavy, but the edges are pretty clean so you can still use smaller grout lines. I'm not familiar with the Tuscan Clay series mentioned above.