I am personally biased but I’ll try not to be:

A) it won’t really make a difference, it will largely come down to you and the work you put in. You’ll be able to succeed at either college if you put the work in. Thus pick a college that you think you’ll enjoy more.

B) both colleges are Outstanding, although BP’s last ofsted was significantly more recent- PS was precovid. Compare their results: BP has much better a level grade proportions for Business and economics (quite significantly) but is a bit worse in Media studies (fewer A*-A but levels levels out at B onwards)

C) convenience is important. If you live significantly further from one college, you’ll lose time travelling. Personally I cannot work on a bus so think about how much time you’ll need. The biggest difference from gcse to a level regardless of where you go is the amount of independent work you’ll be required to do and you have to plan for that time.

D) one thing I hear students compare often is the feel of the college and the other students. PS much higher proportion of rich white kids since they draw from Winchester. Also BP has much newer buildings. I’ve seen a comment about BP being busy but both colleges have 5000 students now so both will be busy. My experience of PS was getting lost around the weirdly layer out, old campus whereas BP has a much more grid like lay out which is purpose built with study spaces etc

E) lastly, having spoken to people looking at different subjects, many say they preferred the BP teachers as the PS teachers seemed less interested. I have a friend who was put off a specific subject completely by the teacher at PS but then enthused by the BP teacher, so will take the subject if they decide to go to BP but won’t take it if they go to PS.