Where does the strength of a French cleat lie?
If you consider the physics of this, the B wedge is going to apply more outward force on the cleat attached to the wall then the A wedge for a given amount of weight supported.  So you might cause the attachment to the wall to fail long before you would be reaching the capacity of the bolt's shear limit.
Generally a relatively shallow angle will give you all the support you need as you really just want it deep enough to keep the supported item from popping off the cleat.
If you are concerned about the amount of weight supported, use a wider cleat not a steeper angle on the cut.
Bottom line: Between your two diagrams, the LEFT one is the better choice.