Water is certainly in short supply in the Hill Country, and with the dormant fairways, it was a lot of fun to play. I have played AGC as well, but to be honest, it has been about 7 years since I played in the member-guest there, and it was back before they lost their bent grass greens and certainly before the fires. My memories aren't that fresh.
That being said, I feel like the elevation changes are more substantial at SO. AGC has a ridge that runs through the property that the clubhouse sits on that comes into play on a few holes (1 tee, 6 green?, 10, 18?), but as a general rule I remember it being more subtle in terms of elevation changes than SO. I recall the greens being more undulating at AGC and more like tilted planes at SO. I think the par 3s are better at AGC, but the par 5s are more interesting to me at SO. All in all, I would be happy at either and think they are both great courses in the same ball park as each other in terms of quality. Stripping away GCA architect bias, I would surprised if one course was preferred more than 6-4 in a "blind taste test" by people on this message board, but I wouldn't hazard a guess as to which would come out on top. If invited for a round at either, I would happily jump in the car and make the drive from Houston.