yes, it is a common misconception amongst the western society that oxford is the cream of the uk's higher education. This tends to have come out of it's past prestiguousness and being popularised in various films and books. In the east however, society has not been used to this higher education malarky, and so tend to award social credibility to the best academic performers. Hence Cambridge is considered Europe's best university by eastern society.
When it comes to Americans, they have their fair share of amazing educational establishments, and so their a main desire to leave their own country tends to be down to prestige and such. Oxford, being the older of the two, is considered to be more presitigous. However as is the case with so many things, it's quality not quantity, and so age is now become less important than what the universities have got to offer. Cambridge is fast establishing itself as THE university of academic excellence in Europe. It is the New Oxford....it has everything Oxford had 150 years ago......so move over Oxford, you've had your day.
Although in fairness....if you go to either cambridge or oxford, you're gonig to a damn good university.