Midday for sweeping, Midnight for tanking, but Dusk overall.
They have equal attack, but Midday has much more speed. It also has access to the move Accelerock, which has priority. However, Midnight has more defense and special defense, along with hp. Although, if you have Dusk form, or can get it, use that. It has slightly less speed than Midday form, and more attack then all of them, and still has Accelerock.