If it's a very small kitchen go with one of your options which have less colors in them. You don't need a busy backsplash in a small space. Bottom right if you want some variation. Otherwise, go with a solid cooler gray tone which isn't DARK.

With the dark cabinets I'd even look for a white glass tile in a subway to minimize grout lines since you say it's a smaller space. Match the grout to the tile.

Small kitchen - less busy. Do something solid - agree with the above actually.

Jenn, have you looked at beveled glass subway tile? It would be so beautiful there and there are several color choices. The big box stores have it on display, as well as tile and flooring stores.

Is it possible to have a microwave installed above stove?
That would free up your counter space.
I like the last pic on right horizontally.

Do you want your backsplash to be the star of your kitchen? Or do you want your kitchen to be the star of your kitchen?

The choices you have made will make the backsplash stand out and be very noticeable. Sometimes it is best to find a plain one that blends into the background and let your kitchen be the star. IMHO.

I am a big fan of plain white subway tile!!!

I like bottom right.

My suggestion for the backsplash would be something white to match the quartz, with light gray grout to match the veins. Daltile Amity might work, or something similar. Install horizontally.

http://products.daltile.com/series.cfm?series=496& 

pick something simple and bright

I agree with the others. The glass tile you have selected are very, very busy and will clash with your beautiful quartz countertop that already has a pattern. Busy pattern on pattern in a small kitchen emphasizes it's small space IMO. Go with something simple. Either continue the countertop material as your backsplash or use a backpainted glass backsplash or a simple white tile (color from your countertop).

https://stylebyemilyhenderson.com/blog/difference-grout-color-can-make-tiles

The first pic on that^^ page looks very cool. It would give you a nice contrast with your dark cabinets.

white 3 x6 subway tile or carrara subway

thank you all!! great ideas, and I appreciate your input!
@cineus, getting the microwave installed above the stove is the thing we've been trying to do, but it's just about impossible without replacing the upper cabinets, as we only have 11" of space available, and we need 18" for a microwave installation (the house was built in 1964)

I am only 5'4" and I am not a fan of the microwave above the stove.

I cook. A lot. And I do not want to reach over hot pans to get to the microwave. I like that my kids, and now my grand kids can "help" cook food in the microwave. I love that at Thanksgiving, I can make gravy and not have someone over my head putting in and taking out stuff from the microwave.

I had a pull out shelf built for stirring food out of the microwave....I love it!!

How about something like this?

It has the multi-colored strip look of many of your original samples, but is lighter overall and a little quieter as there’s less contrast amongst the colors.

Jenn,,,how about something like these

Hello. From the options offered by you, I like the fourth option. But still something like it would be suitable for your kitchen

Thank you everyone, I really appreciate the suggestions!
My problem is that I am REALLY not a fan of subway tile, and while our new countertops are gorgeous (heck, anything is better than the horrible ugly grey tile they replaced), I would really love for the backsplash to make a statement (which is why we chose a more neutral countertop), and I would LOVE for the backsplash to have some metal/stainless steel in it.
Any suggestions in addition to the ones I've posted are welcome!!!

I'm just not a fan of busy backsplashes as generally I think they just overwhelm a kitchen and distract from everything else, not in a good way - especially the teensy mosaic tiles. That said, I think this is pretty dang cool. It's definitely the star of the kitchen. You could carry the design around the rest of the counter.

marble and metal

https://tilebar.com/industrial-asiago-metal-mosaic-tile.html

if you want a mix of metal, stone/glass,,,check out these:

http://www.discountglasstilestore.com/metal-tile-collection/

and if you really want the splash to stand out, look at the Komorebi glass tile. I love the colors they have in this collection.

https://tilebar.com/catalogsearch/result/?q=komorebi

and if you're not on a budget:

look at these metal tiles

https://tilebar.com/collection/metal-tiles.html

I would still advise steering clear of small tiles given the small size of your kitchen.

Stainless steel sheet would look cool with your nice counters and cabinets.

Agree with the posters about a plain white tile. if you really like the back splashes you chose then you can use strips of them instead of the whole thing. Beth's first post is right on the money. Bc you do not have a lot of light and no widow you want that kitchen to be as bright as possible....

Since it's a smaller space just keep similar to what you chose leaning more simple. Not a lot of color going on throughout and or large scale things. You don't have a lot of space to cover so better to go with a style such as Beth's linear idea number 1 or 2.