I would say maybe diet... I currently have a girl and a boy..
For both of them, the moon sign, bioryhtms, and chinese calendar were correct... Which is why I completely consider these when swaying, because they affect me. The moon phase though, has been wrong for both.
I conceived my daughter on a full moon, and my son on a new moon... but the moon signs were both correct.
Also, I would consider timing the LEAST important. With my daughter I DTD 1 day before ovulation, and the day after. I used no douches...
With my son however, I believe it was maybe a few hours after or before ovulation, I wasn't sure. But with him I only DTD once.
I consider the diet most important, although I conceived both my kids with high-sodium, meat, and all those things. Even though I conceived my daughter in a high-sodium diet and hardly ANY calcium, I still would consider it for swaying as the most important.
(About PH I don't know since I never checked it with both my children)