Well... are you consdering boarding or day?
St Paul's offers some boarding places... as does Westminster, which is also academically prestigious.
Good boarding schools include Winchester, Charterhouse, Uppingham, Rugby.
You could apply to the Harrodian school, or Hartwood House, which is an all-sixth form boarding school.
If you are looking for day schools, St Paul's is probably the best choice but you shouldn't disregard Latymer or Tiffin Boy's.
...Oh I just noticed that this was last year's thread.