I feel for you. I don't have kids at either school but I did apply for Parkgate for entry into reception in 2016 for my son. I was super impressed by the pastoral care, the close knit community feel, and the relationship between the parents and the school. I felt that my kid would be cared for and nurtured and encouraged rather than forced to produce results. Unfortunately, in the end I did not take up the place simply because of the lack of boys in the older years. The school clearly starts with a 50:50 boy girl ratio in reception, but that year many boys had left. To be honest, I don't know if it was just that year or if lots of boys leave at 8 years old to go to boys prep schools. It is worth asking the school about this as you also have a boy. Or it might not make a difference to you if he is in a majority female class when he is older. I have a friend with a daughter there and she is very happy and I've only heard good things.
I don't know anything about Eaton House, but check out this thread which was recently posted from a parent wondering if she should move her son from Parkgate to Eaton House (in case you missed it): viewtopic.php?f=6&t=97956