Hopefully staples like Noir, Blanc, Navy, Fauve(!), etc., similar to the lower contrast Noir Circulaire face but perhaps a full screen gradient in the very background edges for the seconds hand—similar to the Hermès Noir and Gradient faces as the seconds hand would be too small for the tiny clock dial—to go with the full-screen Watch OS 10 aesthetic and have a little more variety to the face every time you raise your wrist.
Of course, all of the Hermes colors would be stunning, especially if utilized full-screen! Jaune, Bambou, Azalée…