How to choose between these grammar schools and nearby family areas?

Thanks all for your responses and questions.
Maybe I should have mention some background of us:

We work and live in central London, both with international background, only started living in the UK from studying Master and above degrees. We knew little about the UK system below university, sent our only DS to a local state primary rating Good, although disappointed by the quality of education and some kids’ behaviours, DS is happy there and has friends from all over the world as it’s a very diverse school.
After the pandemic, we considered relocating out of central London to somewhere that is a bit easier to afford a house with nice gardens as WFH is common, but don’t know where to move to. Had a look of some house all over the place, still no idea.
Since DS will move to secondary and we saw his school reports say his very capable academically with great death in both Maths and English reading, we started to think maybe it’s wise to choose where to move to depending on his future school.
There is almost no homework from his primary school, so he had plenty of time to participate in many different clubs (sports, art, music), charities and activities after school time. He’s very energetic, sociable and has many interests, particularly love sports and reading books.
The private school fees are too high and not worth it, the only decent comprehensive secondary here with rigorous discipline is on the boarder of catchment from us, so that’s our backup option, if we are not moving or no success in the 11+.
As I said, we want to move after the primary time to avoid upheaval, and don’t want to make the exams a huge pressure or must for DS, so we only want to consider those schools that don’t restrict where we are living now. After some research, state secondary schools are mainly offering space based on your current address, only a few grammar schools are offering all or partial spaces regardless of your address. So we shortlisted some around London.
Unexpectedly, DS has passed exams for these schools with good scores after a few months of studying on 11+ curriculum once a week in an extra class and he was very much enjoyed study with mind-liked peers in a non disruptive environment. He sat different style of the 11+ exams although only studied the GL version. He said he preferred to attend exams rather than go to school as he could learn more from the exams. So we let him.
We kind of randomly put some top grammar schools that he’s eligible on the SCAF (haven’t even visited all these schools), thinking to see which ones he can be offered then decide where to move to… Now, we have received an offer of one of these, but still have a chance to change our preferences (as he’s likely to be offered via any of the waiting list if there is any space becomes available), so thinking to seeking some advice of schools and especially areas for relocation.
Many thanks.