NP parent here and those are the same two schools we chose between. Super glad we chose Newton in the end, thoroughly impressed by it and I don't think the traditional nature of EH would have suited us.
We live CC Northside so commute would obviously be amazing to EH, but Newton is really not that bad. Loads of buses go down Queenstown road and they get there faster than cars due to the bus lanes - door to door 20 mins on the 156
. And if you drive there's a trick to where you need to park to make life easy.
I wouldn't worry about playdates and proximity - you will spend half your weekends at various party venues around SW London anyway, and these are the same no matter which school. We find any playground we go to from clapham common to Battersea Park and also Chelsea, we run into children we know. If we had just stuck to Clapham common I fear our world would have felt a bit too small too quickly?? Everyone is looking for different things though - good luck with your choice and feel free to pm me