Neither of these cars are very pretty to me. The X5 has a much,much better exterior,while I prefer the interior of the Q7. I'll wait for some head to head reviews before making a vote.
Of these two, the Q7. I don't really see myself buying either even if I had the money, but if I were to buy an SUV, I'd want it to be big and spacious and able to tow a really heavy trailer.