Deciding between Kingston Grammar (KGS), Emmanuel and Whitgift

There is quite a significant geographical difference between Whitgift and KGS. How long your DS is willing to travel for may have an impact on where he'd be happy? If your son is sporty, are you willing to drive your DS to sports events at the school on weekends?

My DD has been in fourth year (year 10) since September after we moved back to London after living abroad. My DS has just received an offer for KGS, amongst other academic schools, and we’re over the moon to be able to send him there this coming September.
We had heard fantastic things about the school before my DD joined, as friends of hers had been there since year 7, and I have to say it has totally lived up to our expectations.
The girls and boys have all been lovely, welcoming, down to earth and fun.
The teaching has been excellent and the leadership team have been very vigilant in terms of ensuring my DD has been sufficiently stretched (e.g. moving her up in science sets and encouraging her to take further maths GCSE). This was unexpected but very welcome!
Overall, whilst we haven’t been there very long, I can’t recommend it highly enough. I’m really happy to be sending my DS there alongside my DD.

Honestly I would just look at the transport options and choose the shortest/quickest from your home.
All are good schools with good sports offerings. If your DS is really talented (significantly above 1st team level) he will be playing with academy/excellence programs outside school anyway.
There are always nightmare stories about pastoral care, bullying, drugs, drinking sex etc. But these things are present in all schools at various times - because they are filled with teenagers. It would be difficult for a London school to survive if they systematically failed to deal with these issues as they arise.

I know their pastoral care is meant to be excellent—honestly, I’ve been asking around about their reputation and I’ve heard nothing but good things, which is so reassuring.

We’re in a very fortunate position with a few other offers, including KGS, so we’re currently weighing everything up! We are very much inclined towards KGS for now, but we’re looking forward to the offer holder days to get a proper feel for the place and see where she’d be happiest.