Actually I purchased both the Syunyata and the Audioquest since well... I had till now not found a power conditioner that I could live with. In my system the Shunyata was much better however, It's my understanding that your local power issues would be the deciding factor between the two. Actually the Youtube channel Audio Excellence (i think out of Canada) tackled this very issue recently and that was the conclusion they reached.
I have good power being only a mile from the substation but have significant noise on the line so the Shunyata was the perfect fit. If you have power fluctuations but it is reasonably clean it's my understanding that the Audioquest would be better. Who knows though. I have found that there are very few absolutes in our hobby as the synergy of the various components of the system is more important that the capability of the components. Your mileage may vary.
I have good power being only a mile from the substation but have significant noise on the line so the Shunyata was the perfect fit. If you have power fluctuations but it is reasonably clean it's my understanding that the Audioquest would be better. Who knows though. I have found that there are very few absolutes in our hobby as the synergy of the various components of the system is more important that the capability of the components. Your mileage may vary.