I debated the two, also. I went with the X5. First off, I personally didn't care for the new look of the MDX coming out. Secondly, being a new model, they probably wouldn't deal too much. (Although, with this economy, who knows.) So, if there's not much incentive on the MDX, and BMW is giving a great deal now on the diesel, they just came out to be too close in price for me. That being the case, I felt the X5 was the much better deal, not to mention a lot better quality SUV. I was looking at the sport model for the MDX.