Deciding between Henrietta Bernette, Brampton Manor and Harris Westminster

Hello,
Wanted to understand something related to A level enrollment in schools. My daughter is deciding between Henrietta Barnett, Brampton Manor and Harris Westminster. Would like to know which one is better in terms of University preparation and overall students support? For A level she is going for Math, Phy, Chem, Bio and for the uni she aspires to apply for Oxbridge and the US universities as well in STEM.
Will be very helpful if somebody could share their thoughts to help her decide.
Regards
Arindam

I'm assuming she wants to do chemistry, biochemistry or biological natsci?

She is keen for bio medical field hence looking forward to take BIo, Chem and Maths for sure. 4th Subject changes as per the subjects available. Which school did u go for finally and what subjects?