The list appears to cover the standard academic boys school options for someone living in Notting Hill and effectively illustrates the range of options available. Different schools will suit different children.
10 years ago Latymer Upper would not have been on the list. It was just about to go co-ed and had been considered the alternative and easier option for boys who were either not prepared for 13+ or unlikely to be selected for a very academic school. It appealed to local children, those not getting Tiffin or other popular state secondaries so seeking a private alternative and those not getting Tiffin and those not wanting to board.
Turning co-ed, an extensive building programme and changes in London demographics have had a huge effect on demand for places. Part of the legacy of the out-going head has been to ensure that this change has translated into improving exam results and higher league table positions. The school, as per your list, is now starting to be considered as an alternative to Eton, Westminster and St Pauls, and at sixth form level as an alternative to Kings or Westminster. It is reasonable to predict increased competition for places will mean results continue to improve. People also appear to be impressed by the new, and surprisingly young, new Head.
The outcome is that getting into the school has become more competitive and a lot more unpredictable. The assumption that it is a fall back for girls not getting SPGS or G&L no longer holds good. The competition for boys is tougher as there are fewer obvious alternatives. 11+ at the best of times is a bit of a lottery and Latymer as a co-ed will have fewer girls and boys places than a single sex schools. It is perfectly possible to be offered a pre-place at Westminster, St Pauls or Eton and not get one at Latymer.
Latymer is very different to say SPGS or Eton. If you are confident that you prefer a busy co-ed former grammar school on a cramped urban site to lots of tradition and playing fields, then it might be wise to be tactical and try for a Prep place at 7+ or 8+. (One way of comparing might be to stand on the Hammersmith tow path on a Saturday morning and watch the Latymer rowers emerge from their boat house with the background of noise from the A4, and then cast a glance over the river to see the St Pauls rowers do the same surrounded by green fields.) Getting into the Prep almost guarantees you a place at 11, but effectively cuts you off from entry to other, 13+, schools.
If you are still uncertain, and 6 is young, you wait till 11 and make your choice once you know who has offered a place. The problem with Latymer then is that the majority of boy applicants will be from state primaries, or preps that only go up to 11, most seeing Tiffin, Hampton, Emmanuel, Kingston Grammar and even Toby Young's Free School, rather than the schools on your list, as alternatives. It is hard for parents and for schools like Wetherby to predict how any one child will fare in a single set of 11+ exams against this different competition.
Unless you are thinking of 7+ or 8+ it is not worth worrying too much at this point. All the schools on your list are good, schools are experienced at picking who will fit, and it becomes clearer as he gets older what school will suit your child.