Fluglehrer

The FAA Airplane Flying Handbook, oddly enough (and to my great surprise), has this interesting statement:

"The key to stall awareness is the pilot’s ability to visualize the wing’s angle of attack in any particular circumstance, and thereby be able to estimate his/her margin of safety above stall. This is a learned skill that must be acquired early in flight training and carried through the pilot’s entire flying career. The pilot must understand and appreciate factors such as airspeed, pitch attitude, load factor, relative wind, power setting, and aircraft configuration in order to develop a reasonably accurate mental picture of the wing’s angle of attack at any particular time. It is essential to flight safety that a pilot take into consideration this visualization of the wing’s angle of attack prior to entering any flight maneuver." (AFH pg 1-6 under "Stall Awareness"; italics mine)

So, you can "understand and appreciate factors such as airspeed, pitch attitude, load factor, relative wind, power setting, and aircraft configuration in order to develop a reasonably accurate mental picture of the wing’s angle of attack", or, you can just use an AOA indicator. On my best days I may be smart enough to juggle all those factors and possibly understand them, but to ask me to also appreciate them is just too much.
...and then to ask me to visualize and develop a reasonably accurate mental picture of the wing's angle of attack prior to entering any flight maneuver? I don't have that many brain cells anymore. I'll take the AOA gauge.