I usually like the DTO challenges. Because they often take you out of your sartorial comfort zone and may even give you a few new ideas as to what fits you.
My idea for a challenge:
Everybody DTO Claghorn.
Because Clags usually posts solid stuff, like blue jackets and grey pants, solid suits and ties etc. Even though we might not have stuff of the same cut or the exact same colour/fabric, I think most of us could find a Clags fit we could (probably with less...