I say Moss vs Detroit. It's a shame, Royal was a promising WR last year, but he's done nothing this year and Oakland has done a pretty good job shutting down the passing games of their opponents. Moss has done nothing either, but I think the game with Detroit will be pretty close, so there should be a lot of throwing, plus Detroit generally gives up a decent amount of points.
Oakland shut down KC and limited SD pretty well. If Royal had shown more in Weeks 1 or 2, I'd give him a shot since Bowe got decent points last week, but Royal hasn't gotten on track yet and somehow I don't see it happening this week either.