Which is the best sixth form out of these three?

so ive got offers from Seven Kings, St Bons &St Angelas and Valentines High. which one is the best one? im looking to either do finance or medicine, so ill do subjects like maths, economics, biology, physics and chemistry and stuff. you see theres all these taster day stuff and i dont know what to do.should i just enrol to all of them and then make a decision later. thanks.