With respect to flying indicated AOA or airspeed on the approach there are a few other factors to consider. First, indicated AOA may be affected by sideslip dependent upon where the sensor is mounted and, therefore, may have an error when flying OEI. Secondly, if you have a wing that has a steep Cl vs alpha curve then a small change in stabilised AOA will equate to a relatively large change in airspeed. Therefore, flying approaches using purely AOA works well for swept wing aircraft but for straight winged types can result in imprecise airspeeds. Also, any rapid pitch control inputs will result in AOA fluctuations whilst airspeed will not change short term. Overall, the optimum technique is to scan both parameters but to bias that scan to one or the other depending on the lift characteristics of the wing and the functionality of the AOA sensing system, with an SOP to calculate the airspeed required for the approach AOA as a function of AUW.
Some aircraft such as the Buccaneer and Phantom FG1 had an audio AOA system so you flew the approach on that rather than using the gauge.