Lou,
Sorry for the late reply.
As I said I prefer Spanish Oaks over Austin GC (barely), and I think what tips it for me is:
1. I like the greens at Spanish Oaks a little more--the steep slopes at #1 and #4, the sunken 5th, massive greens like the 3rd, 13th and 18th, and a super green for a driveable par 4 at #6. Good variety as a set, and the holes can play completely differently each day as the pins are moved around.
2. I like the playing surface at Spanish Oaks a little more--I think the zoysia surfaces at Austin GC work against the intent of the course, especially around the greens. By that I mean this--so many of the green surrounds fall away from the putting surfaces like they do at Pinehurst, and the logical recovery is usually a run-up shot. But the zoysia grass is sticky and unpredictable, and so these shots don't work as well. I also prefer the quick bermuda of SO over the bent grass green surfaces of AGC.
3. I like blind and semi-blind shots, and Spanish Oaks has fun ones at #8, #9, and #18.
But again, for me it is splitting hairs, as I could happily play either every day.