Lol, thought about this earlier today - it would have to be the bag that I am still waiting (and hoping) for - alma mm damier ebene with a strap. If this won't be released it would be the alma mm mono with a strap.
Mine would be Vernis Alma PM in Rouge Fauviste, even though I don't own one! Here's my logic for picking a bag I don't own: Vernis is my favourite line, Alma is my fave style, PM my perfect Alma size, and Rouge Fauviste my favourite vernis colour.