I've been thinking about which measure of quality excels above all the rest and I can't help leaning towards simplicity. Of course, if a system is error-prone yet simple, it's not quite as simple as we expect it to be. Therefore, simplicity only counts when we are dealing with clean systems i.e., no errors. In other words, given two clean systems of differing simplicity, prefer the simpler one.
The odd thing about simplicity, though, is that achieving it requires far more work than less simple equivalent systems. It's all about eliminating unnecessary controls and this requires the creator to hide so much more from the user than ordinary. One of the most iconic examples of this is Face ID on newer iPhone models. Apple integrated the act of unlocking with the act of facing the phone since they coincide (virtually no one uses their phone without facing it) yet achieving this required considerable ingenuity and expertise in making it just work. The fact that I can use Face ID in the dark never ceases to amuse me. (It depends on the invisibility of infra red light.) Also, Apple designed to even work with face masks meaning that only a fraction of what was needed before is sufficient to access bank cards and other secure functions of the phone.