the room is sherwin williams rare grey, and does not have alot of natural light, just not sure which white would go well with this color

I don't really think shiplap would give you much bang for the buck in this space. If it were mine, I'd focus on revamping the artwork on the walls, replacing the mirrors with something that holds personal meaning, and maybe doing something more dramatic with artwork where you have the map. Something that reminds you of favorite travels or places, perhaps? Enlarged personal photos or big original canvas paintings?

Another vote of no shiplap. The additional pics really help with figuring out what the black parts in first pic really are. Nice job on stairs & the entry bench set up. Nelliebean’s idea of wallpaper to cover the wall where you tried filling in the paneling groves is a great one. I think it’s either that or remove the paneling & repair wall if needed. Adding shiplap is another layer of lines and texture on top of the painted paneling & the pattern on stair risers - both of which look great. But adding shiplap is more lines & horizontal ones at that. Way too much. So, back to wallpaper & lighter color of paint.

That would be too dark next to the stone around the fireplace. If you want to change the color of that wall, choose a color from the stone, but I think it looks good painted the same color as the other walls. Every room doesn't need an accent wall, plus it is already an accent with the shiplap. Your mantel looks a little cluttered, and although I like the picture over the fireplace, it doesn't complement the stone very well and looks a little too large.