just my 2cents...most people would actually suggest the college they've been to or are currently studyin at. no one would be able to suggest which one has better A levels. i just finished my A levels in taylors. for me, it was a wonderful experience. lecturers r good even if the lecturer is new. n i read one of the earlier post that classes r large. i disagree as the largest A levels class is only for 1 subject, LAN which isn't really important.
the only difference i know between London Alevels n Cambridge Alevels is that u can retake any paper for any subject in London Alevels. but for Cambridge, if u want to retake a paper u have to retake all papers for that subject u were taking b4. i think cambridge way is better since u will have more motivation to score n not retake. good luck with ur choice