It depends what you want.
Woodcote -not a good record of getting pupils to Eton and Winchester in recent years. Lots of army families, which is not a bad thing but a better balance wood be good I think. Nice, down to earth parents.
Ludgrove - I found this school very cold and parents were dreadful. Not as many boys to Eton in recent years either. Full to capacity because of the prince connection.
Cothill - fabulous school, great French exchange programme, lovely location, great facilities. I know the new headmaster and he will bea great asset to the school.
Horris Hill - sweet little prep, boys very nice and kind and bullying genuinely non-existent. More a school for genteel boys heading to Winchester but does send all over. Facilities more natural (dens in woods, camping) than state of the art.
Sunningdale - uber posh but head great and academically rigorous if a boy is bright.
My choice - Cothill, if you want amazing facilities and opportunites with a good track record of senior school placement. HH if you want your son to be blissfully happy and care-free; it is also the most academic of the schools eventhough it is unselective.