@PDR1
That depends entirely on what you choose for your datum.
A common choice is the so-called "geometric AoA" which uses a line drawn through the TE and the centre of the nose radius (with flaps and slats retracted). This will produce arbitrary numbers because the lift coefficient at "zero" will vary between airfoils and also vary with flap/slat deployment.
Another choice is the so-called "aerodynamic AoA" which is simply a datum where zero degrees AoA is the zero-lift coefficient angle. This could tell you useful things, but it would feel strange because for many airfoils zero aerodynamic AoA will occur at as much as minus 7 or 8 degrees geometric AoA. It would also lose its definition as soon as flaps/slats etc were deployed (unless you recalibrated the datum for each stage of flap, which would be weird).
Thse simplest option, and the one on every aircraft I've been involved in, is to define the "aircraft" angle of attack as being purely in reference to the same fuselage plane to with pitch is referenced. So an aircraft with zero pitch and zero AoA has zero gamma. Making tht simple equation work.
That avoids all the questions about what bits of the wing to use as refences moot - you don't use any of them. (Not only does any wing reference move around as surfaces are deployed, but with washout, which wing station would you use anyway). Since the wing based reference ends up being arbitrary anyway, may as well keep things simple at the aircraft level and use fuselage AOA.
That still leaves to issue of local AOA at any point you might sense it not being truly the same as the nominal AOA. In flight test you 'solve' that with a nice long boom. Otherwise, you calibrate your fuselage mounted sensors/vanes and hopefully get a decent relationship. In any case, as long as the use the AOA is put to is understood in the right context, it doesn't much matter if the relationships are a bit off. (If I define my shaker firing, say, as a function of vane angle and flap, any calibration changes with flap can be masked)