The WR Choice is meant to be a play that lets the Outside WR get open, no matter what the defense does. If the defender is playing inside, then the WR should run up the sideline on a fade. If the defender is playing outside, then the WR should jet to the inside on a slant. If the defense is giving the WR some space, then the WR should just settle down and wait for the ball on a stop route.
The Quarterback needs to have great chemistry with the WR so that they are on the same wavelength and can be expecting each other to make the same read.