i used to have an x5 4.8i, it was awesome. i was sad to sell it, but i like the qx enoguh to make it ok. i've never driven the cayenne.
i like the looks of the q70, in the 5.6 version, but it doesn't get good reviews at all. i think if i were going to spend that much money on a car that size i would get a bmw 550xi.
I'm leaning towards the X5 diesel.. but man, I don't want another note nor do I want to change dealership.. My Infiniti service guys are tops and take good care of me. Worried some other brand won't match up to the level of service I'm expecting.
This Q60 is my first Infiniti; so can't weigh in on Infiniti SUV's. I've had a couple of X5's which were great; however, my favorite was my Cayenne !!!
I suggest you test drive them back to back .... good problem to have.