Go and look, open evenings and daytime tours, and make up your own mind.
TKC is not to everyone's taste, but is improving rapidly thanks to its links with Howard of Effingham, is a small school and does very well with pupils at each end of the attainment level. What happens to the kids in the middle, I am not sure.
Thamesmead is a popular choice for arts-leaning children. The new Yr 7 definately took out-of-catchment, although maybe from the waiting list. Or there are some arts-based places too.
Matthew Arnold has a new head this year, so watch this space - it will probably improve.
Bishop Wand is popular, and the sports facilities are good. Check the surrey admissions booklet to see how many got in under the non-faith category.
St Pauls is rapidly moving in the right direction, and the head is fantastic.
Also look at Magna Carta in Egham. You don't have to apply only to schools in Spelthorne, by the way. And you can apply across the borders too.
You get six preferences on the form. Put the schools down in the order you would like them. The schools are not told where you ranked them, and can only apply the admissions criteria.