With respect to what? The difference between the angle the stab makes with the horizontal in flight versus the angle the wing makes is usually what defines incidence. Then there is also the thrust angle. Really, you can take anything as a reference then relate all angles (thrust, wing, stab etc. ) to that reference. In real planes, this reference line is often called the "Water Line", a throwback to the drafting techniques used when ocean going ships were drafted. Now the angle at which the fuselage is desired to be relative to the horizon in flight is often the reference line. Now, a quick answer to your question, assuming a flat bottom wing, is that the wing should be at a more positive angle than the stab; how much, usually about 2.5 to 4 degrees.