There are a few more choices for these self stick no grout DIY tiles. I like these black, white and soft green mosaics for your space. These at Wayfair.com

I like color and would probably paint the wall something other than gray. A popular blue/green gray is Sherwin Williams Sea Salt. (Close to the second picture) I would probably do a similar backsplash or a neutral backsplash to make it more flexible for changing color schemes. I find gray gloomy living in the northern part of the country.

The third picture has white subway tile which is very affordable. Backsplash is not a large area and you can sometimes get something very pretty because it is a small area.

Really inexpensive - textured, paintable breadboard wallpaper. $20 a roll and very easy to apply.

I agree with changing the wall color to a light gray or other color that better complements your countertop and floors. Consider upgrading your knobs and pulls. It will make a big difference. Subway tile is lovely but ubiquitous; a wood tongue and groove backsplash might be a good look in your kitchen. A rug would really warm things up, too.

I agree on changing the color, have been checking out the colors you all recommended and plan on painting this week! Thank you!

I noticed you have a soffit - I do too. I have a few antique china dishes displayed on mine - I have a vintage look kitchen. (see my idea book) However, very colorful or fun plates in your chosen accent color might be fun or pretty to do the same.

Putting together a kitchen color palette can be challenging!
Here is a great article that might help: Kitchen
Color Palette