i also like the x6m better than the x5m but it's not up to me, also the x6 has a really small cargo space and the back seats is ma sikip. so kawawa ang nasa likod.
the handling of the x5m is really great, i can say just as good as my STi. what impressed me the most is the fuel response, pin point accuracy of the steering wheel and the paddle shift almost has no lag it changes gears just as fast as our c63.
regarding the interior, the x5m's interior feels much more hi-tech than the cayenne but the cayenne felt much more solid than the x5m. the seats of the cayenne are also better and the leather is also better. so they're really not that far apart when it comes to the interior. so the choice will be decided by maintenance cost na lang siguro, but in the states mura lang mag maintain ng bmw i just don't know about porsche.