In general, what holds the heathland courses back for me is that they all feel so similar [originality is so important to me] and that they don't have great greens contouring or exceptional short-game interest. All of the above courses do.
At the end of the day, the Stockbroker Belt course I have the most affection for is Woking. Its greens' internal contours are a stunning contrast to just about everything else in the London area. (Actually, to everything else in the area?)
One thing I have wondered about: I played all the other London area courses, repeatedly and furthermore over a period of years, before coming to Woking. I suspect the revelatory aspect of the course might not have been as strong without the normative experience formed by those other courses. I recall very strongly my first Woking impressions being a kind of reaction against the expectations created by that experience. Part of that was / is down to my knowing Woking as one of the earlier London courses and my assumption that greens must have "progressed" out of the Victorian Age from being less interesting to more interesting and exciting.
Woking therefore felt out of time to me. Its origin date (allowing for Low and Paton's efforts) seemed too early by far. I remember one of my first impressions of the course was that it was sort of Modernist; in comparison the others seemed Victorian. That's not correct in a strictly golf architecture schools sense, I know, but Woking feels different, more modern, more complex, more advanced.
I'm sure there are a number of other normative experiences I've had that contribute to feeling. Experiencing Mackenzie's or Ross's greens for example and thinking of them as the next link in the evolutionary chain.