If you are looking for Luxury, you cant beat the Range Rover HSE. Range Rover Sport is not a proper range rover, so i wouldnt even consider that. I cant really comment on porsche as i dont have personal experience with it. But if you are looking for the best ride quality and handling and safety aspect, i would go with the X5.X5 i would say is also the superior vehicle in terms of technology, i have driven alot of luxury cars and nothing can come close to a bmw with dynamic package, its really unparalleled, especially in harsh weather. I would also like to know how porsche cayenne compares to the X5, specifically in snow. I havent driven a car that tops the X5 with dunlop m3's on in winter.