IMO you do not choose backsplash until you have chosen your counter , not the other way around and I do not like the crackle tile in a busy pattern with either of these choices

Make your choices from the least (appliances) to the most (wall paint colors). That way your choices are always getting larger instead of smaller.

The darker gray is lovely.

Well, I typically tell my clients to get the ctop installed first then pick out your backsplash. However, sometimes a tile strikes someone and we work the other way around. First, what direction does your kitchen face? If it's south you will have lots of bright light throughout the day, if it's north it will tend to be a darker kitchen and perhaps the darker top might make it heavy in there. Are you doing recessed ceiling lights, under cabinet lights? Pendants lights- if so the dark color will not be too dark. In fact, it will offer some contrast. I'm not sure where you live but look for a Cambria dealer and look up Seagrove. It may be a really nice contrast between the two. I LOVE a white on white kitchen but sometimes it's a bit bland. Either way it will be beautiful. Best of luck!

I think you may do best with a medium grey, with some contrast, but not quite that dark. Super dark shows ALL water spots and smudges.