Once you have your floors and cabinets done, then come back and post pictures. It will be a much easier job, once, we can see what you have.

At the very least when asking for assistance, post images of the finishes you are referring to. Do we have to do ALL the work for you?

I think you'll find that most kitchens with SW Peppercorn have white walls and countertops.

If your room doesn't have great natural light, installing upper and lower dark gray cabinets is a big mistake.

I apologize for the lack of knowledge and will post pictures in the future.

Wall color is chosen last. You haven't said what your countertops are. That is an important part of the puzzle as well as the floors and cabinets. Once everything else is done start sampling wall colors. Very dark cabinets are a very specific design choice that won't appeal to everyone, so I hope you're planning on living in this house a long time and as Beverly said, have a lot of natural and artificial light. Otherwise you will be creating a cave. Remember that pictures online and in magazines are photoshopped and lit to look their best and those finishes won't necessarily look the same in your house.

Countertop will most likely be a white quartz.

Perhaps BM White Dove could work, you'll see if it goes with the white of your countertop and backsplash.