I usually stay away from this topic because for me holosync does not work. Quite simply because the CD does not have enough volume for my hearing. I have also used the insight CD, that one with the same high quality headphones and CD player, I can hear and I find it quite pleasant.
Vantage Quest is quite entraining when compared to Insight and Holosync and volume is excellent.
When it comes to these types of tapes and CD's I have a collection and vary which one I use Holosync never comes up as a choice. When I see holosync not working for someone I merely figure that the CD might just be ouside the individuals perferred hearing range. Insight might just work better for them because the CD puts out more volume than Holosync or it's quite possible that neither CD will have much impact.
Holosync - for me- does not work (outside my hearing range) If I'd have known more about it I wouldn't have bought it in the first place.
Insight - for me - nice meditation session (have others I prefer more)
Vantage Quest - for me - very entraining, nice subsitute for my L & D device.
I use 'none' on a daily basis.
Alex