I personally think you have to go with the GTS or higher as far as the Cayenne goes. The base model and the S are just flat out ugly, IMO. I feel the same with MB. Except for the ML 63, none of the ML's do anything for me. The X5 is far better looking and would be more fun to drive compared to the equivalent Porsce or MB, IMO. Unfortunately, the 4.8i is a little underpowered when you get into the realm of the ML 63 and higher end peppers. I guess it will be different when the M versions of the X5 comes out, not to mention the X6. I would bet the playing field will be somewhat leveled then.

Also, Audi doesn't make anything that really competes with the X5 right now and far as looks and driving dynamics are concerned.

Infinity is even further down the list. They are a second tier manufacturer compared to BMW, Porsche and MB, IMO. I don't care how fast the FX is.