I've owned BMWs since 2001 and my first X5 e53 3.0, I bought new in 2005 for my wife and we put just about 100K miles on it and traded it in on a 2013 X5 35i with the Sports Activity Package. I considered getting the diesel, but I don't like noisy cars and diesel is not as generally available as premium gas. Also, I don't see any power advantage or advantages at all other than some say it gets better mileage. We average about 17mpg in stop and go traveling she does to cart our girls to and from school and activities.
Perhaps driving the 35d and 35i will tell you which to get, but I don't really see enough advantages to go diesel.
Here's my Alpine White 35i. My wife loves it.
