Purple. Deep, dark purple, otherwise known as SHADOW (#2117-30)
This one's a big contrast from Benjamin Moore's 2016 choice. That was SIMPLY WHITE!
But wait...it changes, depending on the light.
Makes it much more interesting, not to mention versatile.
(Yes, it's the same paint in both photos.)
Apartment Therapy's got some suggestions how to use this deep, dark color... but I'd say you really need light to pull it off successfully, like the strong uplighting used in the staircase photo. Plus windows. Lots of windows. Otherwise, it's going to feel like a cave in your home of choice.